Printing apparatus controlling advancement of printing paper, actuation of a hammer, and advancement of an ink ribbon

ABSTRACT

A printing apparatus comprises a type wheel carrying a plurality of type elements and a platen for mounting and advancing a printing paper. A hammer can strike any one of the type elements against the printing paper and an ink ribbon is positionable between the type elements and the paper to imprint a character on the paper when any one of the type elements is struck. The ink ribbon is advanced by a driving mechanism. First, second, and third selecting systems respectively select one of a plurality of degrees of advancement of the printing paper, one of a plurality of time intervals of actuation of the hammer, and one of a plurality of amounts of advancement of the ink ribbon. First, second, and third counters each count pulses from respectively associated first, second, and third pulse generators to, respectively, first, second, and third set values determined by the selected degree of paper advancement, time interval of hammer actuation, and amount of ribbon advancement. First, second, and third control circuits respectively start paper advance, hammer actuation and ribbon advance upon selection by the corresponding selecting systems and stop such paper advance, hammer actuation and ribbon advance when the corresponding counter counts to its set value. The three control circuits are operated in a coordinated manner by a microprocessor.

This application is a continuation of application Ser. No. 523,442 filedAug. 15, 1983, now abandoned, which is a divisional of patentapplication Ser. No. 314,441, filed Oct. 23, 1981, now abandoned.

BACKGROUND OF THE INVENTION

1. The present invention relates to a serial printing apparatus in whichthe font wheel and the carriage are stopped before each printing action,and more particularly to such printing apparatus provided with systemsfor controlling advancement of printing paper, actuation of a hammer,and advancement of an ink ribbon.

2. Description of the Prior Art

The conventional large word processor with a cathode ray tube display isbulky, expensive and requires expertise in use. Also there are knownelectronic typewriters which function as small word processors but theyare still associated with various shortcomings requiring improvementsand are complicated and expensive in structure.

SUMMARY OF THE INVENTION

The object of the present invention is to provide certain improvementson such apparatus.

BRIEF DESCRIPTION OF THE FIGURES

The attached Figures illustrate an embodiment of the electronictypewriter of the present invention, wherein:

FIG. 1 is a schematic perspective external view of the electronictypewriter;

FIG. 2 is a schematic perspective view showing the internal structurethereof;

FIGS. 3A and 3B are cross-sectional and lateral views respectively of acarriage unit shown in FIG. 2;

FIG. 4 is a perspective view showing the positional relationship betweena ribbon cassette and a ribbon detector;

FIG. 5 is a lateral view showing the cassette position in a print actionand in a stand-by state;

FIG. 6 shows the manner in which FIGS. 6-1 and 6-2 should be arranged;

FIGS. 6-1 and 6-2 are block diagrams of the entire control systemgrouped in various functions;

FIG. 7 is a detailed block diagram of the printer control unit shown inFIG. 6-1;

FIG. 8 is a circuit diagram of the paper feed pulse motor control unitshown in FIG. 7;

FIGS. 9 and 11 are circuit diagrams of the printing hammer control unitshown in FIG. 7;

FIGS. 10 and 12 are circuit diagrams of the ribbon feed motor controlunit shown in FIG. 7;

FIGS. 13 and 14 are circuit diagrams respectively of the bail startmotor drive unit and the carriage indicator unit shown in FIG. 7;

FIG. 15 is a circuit diagram of the alarm control unit shown in FIG.6-2;

FIG. 16 is a circuit diagram of the type selecting motor control unitshown in FIG. 7;

FIG. 17 is a circuit diagram of the carriage driving motor control unitshown in FIG. 7;

FIG. 18 shows the manner in which FIGS. 18-1 and 18-2 should bearranged;

FIGS. 18-1 and 18-2 are circuit diagrams showing an example of a keyinput circuit;

FIG. 19B shows the manner in which FIGS. 19B-1 and 19B-2 should bearranged;

FIGS. 19A, 19B-1 and 19B-2 are waveform charts showing the functionthereof;

FIG. 20 is a detailed plan view showing an example of the control panelof an electronic typewriter shown in FIG. 1;

FIG. 21 is a detailed view of the flag group shown in FIG. 6-2;

FIG. 22 is a detailed view of the register group shown in FIG. 6-2;

FIG. 23 is a detailed view of the line buffer shown in FIG. 6-2;

FIGS. 24 and 25 are control flow charts for said line buffer;

FIG. 26 is a control flow chart for key operations at the registrationof characters or a sentence;

FIG. 27 is a flow chart showing the function thereof;

FIG. 28 shows the manner in which FIGS. 28-1 and 28-2 should bearranged;

FIGS. 28-1 and 28-2 are control flow charts for key operations at thereviewing of characters or a sentence;

FIG. 29 shows the manner in which FIGS. 29-1 and 29-2 should bearranged;

FIGS. 29-1 and 29-2 are flow charts showing the function thereof;

FIG. 30 is a schematic view showing an example of the printing sheet;

FIG. 31 is a control flow chart for key operations at the registrationof page format;

FIG. 32 is a control flow chart for key operations at the recalling ofpage format;

FIG. 33 is a control flow chart for key operations at the registrationof tabulator stop positions;

FIG. 34 is a control flow chart for key operations at the recalling oftabulator stop positions; FIG. 35 shows the manner in which FIGS. 35-1and 35-2 should be arranged;

FIGS. 35-1 and 35-2 are flow charts showing the functions ofregistration of page format and tabulator stop positions;

FIG. 36 is a flow chart showing the functions of recalling of pageformat and tabulator stop positions;

FIG. 37 is a schematic view showing an example of printing;

FIG. 38 is a block diagram of an embodiment for obtaining the contentsof a line buffer as shown in FIGS. 39-1 and 39-2;

FIG. 39 shows the manner in which FIGS. 39-1 and 39-2 should bearranged;

FIGS. 39-1 and 39-2 are views showing an example of the content of linebuffer;

FIG. 40 is a schematic view of an example of the printing head of thepresent embodiment;

FIGS. 41 and 42 are schematic views showing examples of printing;

FIG. 43 is a block diagram showing a circuit for conducting saidprinting;

FIG. 44 is a block diagram showing an embodiment of the invention;

FIG. 45 is a schematic view showing the thus obtained print;

FIGS. 46A and 46B are schematic views showing the changes in the displayand print;

FIG. 47 shows the manner in which FIGS. 47-1 and 47-2 should bearranged;

FIGS. 47-1 and 47-2 are block diagrams showing another embodiment of theelectronic typewriter; and

FIG. 48 is a view showing another embodiment of the keyboard.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Now the present invention and its various features will be clarified indetail by the following description to be taken in conjunction with theattached Figures.

At first reference is made to FIGS. 1 to 5 showing the basic structuresof an electronic typewriter embodying the present invention, wherein aplaten knob 1 is provided for manual loading of an unrepresentedprinting sheet or for fine adjustment of the print position in thevertical direction. Said knob 1, when pressed inwards, is disengagedfrom a stepping motor 14 (FIG. 2) to allow manual rotation of saidknob 1. A paper support 2 guides the printing sheet in such a mannerthat the printed face of even a thin sheet is directed toward theoperator. A page end indicator 3 is a scale indicating the length to thelast line of the sheet and is manually adjusted in advance by theoperator in the vertical direction indicated by the arrow, whereby theposition of the last line can be known when the upper end of theprinting sheet coming out from a platen 17 (FIG. 2) reaches a determinedscale line on the indicator 3. A paper bail 250 (FIG. 2) maintains theprinting sheet in contact with the platen 17. A release lever 4 (FIG. 1)releases pinch rollers 17a, 17b and 17c (FIG.2) provided under theplaten 17, thus allowing the inclination of the printing sheet to bemanually corrected. A cover 5, made of transparent acrylic resin,reduces the noise of impact printing and still allows the operator tosee the printed characters. An upper cover 6, 7 can be swung open to theback for replacement of a typefront wheel 30 or a ribbon cassette 36mounted on a carriage 26 as shown in FIG. 2. The printing hammer 32,printing ribbon 34, correcting ribbon 33, winding spool 38, and steppingmotor 39 are discussed later in connnection with FIGS. 3A and 3B.

The illustrated electronic typewriter can achieve four printing pitchesin the lateral direction, i.e. 10, 12 or 15 characters per inch orproportional spacing in which the printing pitch is variable accordingto the size of each type. A scale 8 has three gradations, represented onscales 8a, 8b and 8c, respectively for 10, 12 and 15 characters perinch. An indicator mount 11 mounted on the carriage 26 as shown in FIG.2, holds a carriage indicator 12 which lights a light-emitting diode,12a, 12b, or 12c, respectively, corresponding to a printing pitchinstructed from a keyboard 10 to indicate the carriage position on saidscale 8a, 8b, or 8c, respectively.

The keyboard 10 is composed of character keys 10a for enteringcharacters, control keys 10b, 10c provided on both sides, mode keys 10d,10g provided on both sides and locking slide keys 10e, 10f for selectingthe print modes, and the entered key signals are identified by akeyboard control unit 24 (FIG. 2) and supplied to a main control unit 22(FIG. 2) containing a microprocessor unit (MPU) which is shown in FIG.6-1 as element 44. In case of key entries for printing, related data aresupplied from the unit 22 to a printer control unit 16. A block diagramfor the printer control circuit is shown in FIG. 6-1 and will bediscussed later. In case of key entries for display, related data aresupplied from the unit 22 to a display control unit 48 for display on adisplay unit 9. A block diagram for the display control circuit is shownin FIG. 6-2 and will be discussed later. Also in case of key entries forchanging the LED (light-emitting diode) display units L1, L2, L3, L4,and L5 on the keyboard 10, such as changing the printing pitch(indicated by L1), line spacing (indicated by L2), or characterselection keys (indicated by L3), data for controlling LED's L1-L5 aresupplied from the main control unit 22 to the keyboard control unit 24.A paper feed stepping motor 14 for advancing the printing sheet rotatesplaten 17 through a transmission belt 15 under the control of theprinter control unit 16.

A servo motor 18 for carriage displacement causes the lateraldisplacement of the carrige 26 along guide rods 25 and 27 through gears20 and a belt 21. A photoencoder 19 for detecting the rotation angle ofsaid carriage driving motor 18 provides a feedback signal to the printercontrol unit 16, thus constituting a servo control loop. A back-upbattery 23 for the memory 54 (FIG. 6-2) in the main control unit 22prevents the loss of stored information when the power supply is cutoff. A loud speaker 42 is provided for giving a sound alarm and iscontrolled by an alarm control unit 49. A power supply unit 13positioned behind the printer supplies electric power to various units.A flexible conductor FL supplies signals to the stepping motor 39 etc.on the carriage 26.

FIGS. 3A and 3B show the structure of carriage 26 in cross-sectional andlateral views. In the cross-sectional view in FIG. 3A, there is shown aservo motor 29 for character selection, which is provided on an endthereof with a typefont wheel 30 and on the other end thereof with aphotoencoder 35. A printing hammer 32 is composed of a linear motor 32ain which the driving direction of the hammer 32 is varied according tothe direction of the energizing current in the coil 32b. In the movementtowards the platen 17 said hammer 32 hits a selected type of thetypefont wheel 30 against the printing sheet on the platen 17 through aprinting ribbon 34 in the printing action or through a correcting ribbon33 in a correcting action. In the lateral view in FIG. 3B, there isshown a printing ribbon cassette 36 in which is provided a printingribbon 34 (as shown in FIGS. 2, 3A, and 4), which is advanced by adetermined amount in each printing action by a stepping motor 39. On anarm portion 36a of the ribbon cassette 36, as shown in FIG. 4, is areflecting plate 41 for indicating the species of the printing ribbon34, and correspondingly the carriage 26 (FIG. 3A) is provided with areflective photodetector 40. Under the ribbon cassette 36 is a frame 37(FIG. 3B) for the correcting ribbon 33 on which is mounted a supplymechanism 33a for said ribbon 33 supporting a winding spool 38 (FIG.3B). The mechanism 33a operates on said spool 38 to take up thecorrecting ribbon 33. Said ribbons 33 and 34 are moved to a desiredposition when required by energizing solenoids 28 (FIG. 3A) and 31 (FIG.3B), respectively, to raise the print ribon cassette 36 alone, and toraise both the correcting ribbon frame 37 and the print ribbon cassette36 together.

FIGS. 4 and 5 show the positional relationship of the ribbon cassette 36in the print action and in the stand-by state, and of the photodetector40. In the stand-by state said detector 40 detects the presence orabsence of the reflecting plate 41 in the arm portion 36a of thecassette 36. When the solenoid 31 is not energized and the photodetector40 produces a signal indicating the presence of a reflecting plate 41,the printer control unit 16 invokes the proportional spacing processdiscussed more fully in connection with FIG. 12. When the detector 40produces a signal indicating the presence of said reflecting plate 41,which means that the cassette 36 contains a single-use ribbon 34, theprinter control unit 16 controls the pulses to the stepping motor 39 forwinding the printing ribbon 34 in response to the signal from thedetector 40 to modify the advancing amount of the ribbon 34 according tothe width of the characters printed. Also in the absence of said signalfrom the detector 40, which means that the cassette 36 contains amultiple-use ribbon 34, the printer control unit 16 so controls saidribbon advancing stepping motor 39 as to advance the ribbon 34 by aconstant amount. The rotating shaft 39a (FIG. 4) of the ribbon advancingstepping motor 39 is connected for example with a ribbon drive shaft 39b(FIG. 5) to control the advancing amount of the ribbon 34 according tothe rotation of said motor 39. In a print action the solenoid 31 aloneis energized to lift the print ribbon cassette 36 alone throughconnecting means 31a (FIG. 3B) as represented by broken lines in FIG. 5,whereby the printing ribbon 34 becomes positioned facing the uppermosttypefont on the typefont wheel 30. The position of the printing hammer32 and the platen 17 are also shown. In this state the detector 40 nolonger faces the reflecting plate 41 but faces the printing ribbon 34passing through the arm portion 36a of the cassette 36. Said ribbon 34is provided at the end portion thereof with a reflecting member 34a suchas aluminum foil, whereby the printer control unit 16 identifies the endof the printing ribbon 34 when a signal is obtained from the detector 40while the solenoid 31 is energized.

In a correcting operation the solenoid 28 shown in FIG. 3A is energizedto lift the correcting ribbon frame 37 together with the printing ribboncassette 36 thereby bringing the correcting ribbon 33 in front of theuppermost font position of the typefont wheel 30. The printing hammer 32is activated in the same manner as in the printing action to correct thealready printed character by "lifting off" or "covering up".

The control for the printing and for the display of the above device isexplained in the following. FIG. 6 shows the manner in which FIGS. 6-1and 6-2 should be arranged.

FIGS. 6-1 and 6-2 show basic block diagrams around the main control unit22 for printing control and display control, respectively. As shown inFIG. 6-1 a microprocessor unit (MPU) 44 identifies the key signalsreceived from the keyboard 10 through data bus DB and performs controlof the print unit 43, as well as of the display unit 9, sentence memory54, and loud speaker 42 as shown in FIG. 6-2, according to the sequencecontrol programs stored in a read-only memory (ROM) 53. An addressdecoder 45, under the control of the MPU 44 through an address bus AB asshown in FIG. 6-1, generates signals SELROM, SELBF, SELREG, SELM2,SELFF, SELM1, SELKEY, SELPRT, SELDISP, and SELBZ to respectively controlthe ROM 53, line buffer 52, register group 51, secondary memory 57, flaggroup 50, sentence memory 54, keyboard control unit 24, printer controlunit 16, display control unit 48, and alarm control unit 49. The displaycontrol unit 48 can provide an interruption signal INT to the MPU 44when necessary, as explained more fully n connection with FIG. 18-1. Theprinter control unit 16 in turn provides signals to a motor M of theprint unit 43 through a motor drive MD. The keyboard control unit 24also provides signals to an LED matrix 89 through a cathode driver 64,the operation of which will be more fully explained in connection withFIG. 18-2. The keyboard 10, display unit 9, print unit 43, sentencememory 54, read-only memory (ROM) 53, etc. have respective addresses forprocessing by the MPU 44.

The function of the components shown in FIG. 6-2 will now be explained.The flag group 50 stores the designated state and various modes of thetypewriter. The register group 51 is used for storing for example theintermediate results of the processing. The line buffer 52 stores theinformation of characters already printed and to be printed in theline-unit or word-unit printing mode. In the correcting operation theMPU 44 retrieves the already printed characters from said line buffer 52and automatically performs the corrections. The sentence memory 54stores sentences, characters, tabulator group information, etc. with orwithout title names entered by the operator according to a certainprocedure (which is explained in connection with FIGS. 28-1 and 28-2),and is backed up by a battery 23 against information loss when the powersupply unit 13 is cut off. Said battery 23 is inspected by a sensor 56and an inspection unit 55 as long as the power supply unit 13 is turnedon, and an alarm is given to the operator through alarm control unit 49and loud speaker 42 in case of a voltage decrease for example due to theexpiraton of the service life of the battery 23. The secondary memory57, similarly backed up by the battery 23, stores various modesimmediately prior to the turning off of the power supply unit 13.

FIG. 7 shows the details of the printer control unit 16, whereinprovided are a microprocessor unit (MPU') 110; an interface 111 forreceiving instructions from the microprocessor unit 44 for the entirecontrol and transmitting the information on the printer during the printfunction thereof to said microprocessor unit 44; a work memory 112 forstoring information data etc. generated by the MPU' 110; a read-onlymemory (ROM') 113 for storing the control programs for the MPU' 110; anaddress bus AB; an address decoder 114 for generating various signalsdesignating various control loads such as the motors and solenoidshaving addresses allotted thereto; a ribbon solenoid control unit 109for controlling the solenoids 31 (FIG. 3B) and 28 (FIG. 3A) fordisplacing the printing ribbon 34 and correcting ribbon 33,respectively, a detecting unit 116 including the detector 40 shown inFIG. 4 for identifying the species of the printing ribbon 34 and the endpoint of said ribbon 34, said detecting unit 116 supplying data to theMPU' 110 through a bus driver 115 in response to a request from the MPU'110; and control units 117, 118 for the type selecting motor 29 (FIG.3A) and the carriage drive motor 18 (FIG. 2) respectively, which rotatessaid motors 29 and 18 by determined angles instructed by the MPU' 110and transmit signals thereto through the bus driver 115 upon completionof said rotation.

There are also shown a paper feed pulse motor control unit 119 fordriving the stepping motor 14 for sheet advancing according to thenumber of pulses supplied from the MPU' 110; a printing hammer controlunit 120 for energizing the printing hammer 32 during a periodinstructed by the MPU' 110; a ribbon feed motor control unit 121 fordriving the ribbon feed stepping motor 39 for advancing the ribbon 34according to the number of pulses supplied from the MPU' 110; a DC bailstart motor drive unit 122 to be actuated by the instruction from theMPU' 110 to liberate a paper bail 250 pressing the printing sheet; alatch circuit 123 for selectively lighting one of three light-emittingdiodes 12a, 12b, and 12c constituting the carriage indicator 12 througha carriage indicator drive unit 124 in response to the data from theMPU' 110; a character position table 125 composed of a read-only memoryfor converting the key signal transferred from the MPU 44 to MPU' 110into positional information of a corresponding character on the typefontwheel 30 relative to a reference index position thereon; and a printingpitch table 126 which is utilized, in the proportional spacing mode, todetermine the type spacing or the amount of lateral displacement of thecarriage 26 according to the width of each type and has memory contentsas shown in the following:

    ______________________________________                                        Type       A         B     a       i   ,                                      Type spacing                                                                             1         1     3/4     1/2 1/2                                    ______________________________________                                    

Also in case the detector 40 identifies a single-use ribbon, the ribbonadvancement is controlled to the width of each character in order tominimize the ribbon consumption, and said printing pitch table 126 isalso utilized for determining the amount of ribbon advancement.Furthermore, in case the typefont wheel 30 is changed, the table 126 isutilized to enable variable ribbon advancement optimum for eachcharacter of each typefont wheel 30.

A printing pressure table 127 is utilized for controlling the energizingperiod of the hammer 32 according to the size of characters in order toobtain a uniform print density, and stores a hammer energizing periodsuch as 2 msec. or 1.5 msec. for each character in a manner similar tothe aforementioned printing pitch table 126. Generally the typefontwheel 30 is changed according to the character size or the characterpitch, and the content of said printing pressure table 127 should alsobe changed accordingly. However a memory of a large capacity will berequired for providing the printing pressure tables for all the pitches.For this reason, in order to economize the memory, there is providedonly one printing pressure table 127 for a particular typefont wheel 30,and other tables are obtained by multiplying coefficients in the MPU'110 in response to the information of character pitch supplied from theMPU 44.

FIG. 8 shows the details of the paper advance pulse motor control unit119 (FIG. 7) for the paper feeding stepping motor 14, wherein providedare an oscillator 170 oscillating at a frequency meeting theself-starting frequency of said stepping motor 14; an AND gate 171; apresettable subtracting counter 172; a circuit 173 (comprising threeinverters 173' and a NAND gate 173") for detecting a count zero state ofthe counter 172, providing an L-level, that is LOW-level, output signalupon detecting said state; exclusive OR gates 174, 176; D-typeflip-flops 175, 177 constituting a pulse generating circuit for 2-phaseforward/reverse drive of the stepping motor 14; a stepping motor driver178 (including four single-input AND gates 178'); and a 4-phase steppingmotor 14.

In response to a sheet feed instruction including the amount of sheetfeeding supplied from the keyboard 10 through the MPU 44, the MPU' 110sets the feeding direction in the latch 123 and the feed amount in thecounter 172. If the feed amount is not zero, the zero detecting circuit173 releases an H-level, that is HIGH-level, output signal to open theAND gate 171, whereby the counter 172 counts the output pulses of theoscillator 170 by subtraction until the count reaches zero. The outputsignals of the oscillator 170 transmitted through the AND gate 171 aresupplied to a pulse generating circuit composed of elements 174, 175,176, and 177 for driving the stepping motor 14 to generate pulses of anumber stored in the counter 172, thereby rotating the stepping motor 14by the instructed amount in a direction stored in the latch 123.

FIG. 9 shows the details of the printing hammer control unit 120 shownin FIG. 7, wherein provided are an oscillator 180; a subtracting counter181; a zero detecting circuit 182 (comprising three inverters and an ANDgate) releasing an H-level signal in response to the zero count of thecounter 181; a set-reset type flip-flop 183; AND gates 185, 186; aninverter 184; and a printing hammer 32. In response to the printinstruction supplied from the MPU 44, the MPU' 110 controls the typeselecting motor 29 in the aforementioned manner through the characterposition table 125 shown in FIG. 7, thereby stopping the typefont wheel30 at a desired position. Then, for the printing action the MPU' 110stores "1" in the latch 123, opens the gate 185, refers to the printingpressure table 127 and stores the hammer energizing period for eachcharacter obtained therefrom in the counter 181. Also the flip-flop 183is set by the set signal to said counter 181. As the AND gate 185 isopened, a transistor 187 is activated to drive the printing hammer 32for a period corresponding to each character, thus performing theprinting action with optimum pressures. In the standby state betweenprint instructions, a "0" signal is provided from the latch 123 to theAND gate 185, which is closed. The same "0" signal is received by theinverter 184, which supplies a "1" signal to the AND gate 186. As theAND gate 186 is opened, a transistor 188 is activated to retract theprinting hammer 32 from the typefont wheel 30.

Now FIG. 10 shows the details of the ribbon feed motor control unit 121(FIG. 7) for the ribbon advancing stepping motor 39. Pulses of aninstructed number are generated in the same manner as in the circuit ofFIG. 8 for the sheet advancing motor 14, except that the D-typeflip-flops 194, 195 are so arranged as to generate pulses for 2-phasedrive in the forward direction alone.

In case the signal from the ribbon detector 40 indicates a multiple-useribbon 34, the MPU' 110 sets a constant value in the subtracting counter192 to perform a constant ribbon feeding. Also in case said signalindicates a single-use ribbon 34, the MPU' 110 detects the width of theprinted character from the printing pitch table 126 shown in FIG. 7 andsets a corresponding pulse number for ribbon advancing in the counter192. If the advancing amount is not zero, the zero detecting circuit 193(comprising three inverters 193' and a NAND gate 193") provides anH-level signal to open the AND gate 191, whereby the counter 192 countsthe output pulses from the oscillator 190 until the count zero state. Inthis manner the stepping motor 39 is driven through the flip-flops 194,195 and a stepping motor driver 196 (including four single-input ANDgates 196') by pulses of a number stored in the counter 192.

FIG. 11 shows an embodiment of the printer capable of providing uniformprinting from various typefont wheels 30 (10K, 12K, 15K), by utilizationof a printing pressure table 127 to regulate the printing hammer controlunit 120.

The conventionally known apparatus of this sort, such as the electronictypewriter, utilizes typefont wheels with different character sizes forexample for character pitches 10, 12, and 15 characters per inch, andeven in each wheel there are types of different sizes, so that unevendensity is unavoidable if the printing is performed with a constantpressure. On the other hand, in order to store the information ofprinting pressure there is required a memory of an extremely largecapacity, leading to an elevated cost.

The present embodiment provides a printing apparatus not associated withsuch drawback and capable of providing uniform density from an arbitrarytypefont wheel 10K, 12K, 15K, etc. by means of two read-only memoriesROM1, ROM2, each of limited capacity.

FIG. 11 shows said embodiment in a block diagram, wherein a printinghammer H, when activated by a hammer solenoid HS, performs the printingaction in the known manner by hitting a type 12C of a typefont daisywheel 12K, which is provided with types for printing 12 characters perinch and is replaceable for example by other typefont wheels 10K or 15Kfor printing 10 or 15 characters per inch.

Since each character has a different area in the typefont wheels 10K,12K and 15K, as shown, for example, by type 10C on typefont wheel 10K,it is desirable to regulate the printing pressure of the hammer Haccordingly in order to obtain uniform print quality.

It is also desirable for obtaining uniform print quality to usedifferent pressures for example for a large type "A" and for a smalltype ",", even within the same typefont wheel.

For this purpose there can be provided a memory for setting a particularprint pressure, for example a particular hammer energizing period foreach character, but such memory has to be of a large capacity if theinformation for the printing pressure is stored for all the types in allthe typefont wheels 10K, 12K, 15K. It is however possible to avoid anexcessive capacity by providing a read-only memory ROM1 for the typefontwheel 10K for printing 10 characters per inch and by calculating thehammer energizing times for other typefont wheels 12K, 15K, etc. fromthe information stored in said memory ROM1 for the wheel 10K.

Thus the memory ROM1 stores the hammer energizing times 2 msec., 1.8msec., 1.5 msec., etc. in the coded forms for the types A, B, C, . . . ,a, . . . as shown in FIG. 11.

Also another read-only memory ROM2 stores the coefficients 1, 0.9, 0.8,etc. in the coded forms respectively for the typefont wheels 10K, 12K,15K, etc.

There are also provided a multiplier MLT, a subtracting counter DK, anoscillator OSC, and a flip-flop FH. Now, upon mounting for example ofthe typefont wheel 12K in the printing unit, a typefont wheel detectorKS identifies said mounting by a code mark M12 on the wheel 12K anddesignates an address corresponding to 12K in the memory ROM2. When thetypefont wheel 12K is rotated and a desired type 12C is brought to theposition of the hammer H by the known character selecting operation, anaddress corresponding to said type 12C in the memory ROM1 is designatedto supply the corresponding hammer energizing period, for example 2msec., for "A" or 1.8 msec. for "a", to the multiplier MLT. Themultiplier MLT also receives the coefficient 0.9 corresponding to thetypefont wheel 12K from the memory ROM2 to effect a multiplication suchas 2×0.9 or 1.8×0.9, and the result is stored in the subtraction counterDK in synchronization with a print instruction PO.

Simultaneously the flip-flop FH is set by said print instruction PO toenergize the solenoid HS, thereby initiating the motion of the printinghammer H.

The subtracting counter DK step reduces the content thereof in responseto each output signal from the oscillator OSC, and releases an outputsignal upon reaching zero count state to reset the flip-flop FH, therebyterminating the function of the printing hammer H. In this manner theset period of the flip-flop FH is changed according to the result ofmultiplication to regulate the energizing period of the printing hammerH thereby differentiating the printing pressure for each typefont wheel,10K, 12K, or 15K. Also the characters within a typefont wheel can beprinted uniformly as the hammer energizing period is regulated for eachcharacter, 10C for example, in the typefont wheel, 10K for example.

The instruction for the typefont wheels 10K, 12K, and 15K can also besupplied from the keyboard (not shown).

As explained in the foregoing, the present embodiment allows obtainingbeautiful printing with a uniform printing pressure for all the typesand in all the typefont wheels of different character sizes with alimited amount of stored information, by storing the information ofprinting pressures for the types of a determined typefont wheel and bymultiplying a suitable coefficient corresponding to the selectedtypefont wheel thereby obtaining optimum pressures matching the typesizes and thus effecting the pressure control in the printing operation.

Now reference is made to FIG. 12 showing an embodiment of the printercapable of varying the type spacing corresponding to the size ofdifferent characters on a typefont wheel 30, by utilization of aprinting pitch table 126 to regulate the carriage driving motor controlunit 118.

The conventional apparatus of this sort utilizing a single-use printingribbon is inevitably associated with the waste of printing ribbon sincethe advancing amount thereof is determined to a type of largest width,which is usually "--".

The present embodiment provides a printer capable of achieving maximumeconomy in the printing ribbon, particularly the single-use printingribbon, with a simple structure.

The type spacing information, utilized for controlling the lateraldisplacement of the carriage 26 in the proportional spacing mode inwhich the type spacing is made variable according to the character size,in fact represents the width of types and is utilized in the presentembodiment for controlling the advancing amount of the printing ribbon34, thereby reducing the consumption thereof. In the use of the typefontwheels 12K or 15K with smaller types for printing 12 or 15 charactersper inch respectively, the above-mentioned information is multiplied bythe coefficient of each typefont wheel 12K, 15K to further reduce theribbon consumption.

FIG. 12 shows said embodiment in a block diagram, wherein shown are theprinting ribbon IR; a feed roller FR therefor; a stepping motor PM foradvancing said ribbon; typefont wheels 10K, 12K, and 15K respectivelyfor printing 10, 12, and 15 characters per inch; a typefont wheeldetector KS; a read-only memory ROM1' storing the character widthinformation for the types on the typefont wheel 10K for example in theform of numbers of steps 6, 5, 3, etc. of the stepping motor PM; aread-only memory ROM2 storing coefficients 1, 0.9, 0.8, etc. for thetypefont wheels 10K, 12K, 15K, etc. having code marks M10, M12, M15,etc., respectively to be multiplied by the character width informationstored in the memory ROM1'; a multiplier MLT for multiplying thecharacter width information stored in ROM1' by the coefficients storedin ROM2; a subtracting counter DK; an oscillator OSC for generatingsubtracting pulses; a flip-flop FP for controlling a gate G; and a motordriving pulse generator PG.

In case the wheel 10K is mounted on the printing unit, the detector KSidentifies the code mark M10 of said wheel 10K and designates an addressfor said wheel 10K in the memory ROM2 thereby supplying a coefficient"1" to the multiplier MLT. Then the typefont wheel 10K is rotated toperform the character selecting operation in the known manner, and theprinting hammer H is activated when a desired type 10C or 12C (FIG. 11)is brought to the printing position to perform the print action.Subsequently an address in the memory ROM1' corresponding to the printedcharacter is designated, and the character width information in saidaddress, for example "6" for a character "A" or "5" for "a" is suppliedto the multiplier MLT for conducting a multiplication such as 6×1 or5×1. Then the result of said multiplication is stored in the subtractingcounter DK in synchronization with the ribbon advancing instruction IRF.Simultaneously the flip-flop FP is set to open the gate G, whereby thestepping motor PM initiates rotation by the pulses from the pulsegenerator PG to advance the printing ribbon IR. The subtracting counterDK step reduces the content thereof in response to each output pulsefrom the oscillator OSC, and releases an output signal upon reachingzero count state to reset the flip-flop FP, whereby the gate G is closedto terminate the rotation of the stepping motor PM, thus stopping theadvancement of the printing ribbon IR. In this manner the set period ofthe flip-flop FP is changed according to the result of saidmultiplication, thus regulating the functioning period of the steppingmotor PM and thereby controlling the advancing amount of the printingribbon IR corresponding to the pitch of each type.

Also in case the typefont wheel is changed to 12K, a coefficient 0.9 inthe memory ROM2 is supplied to the multiplier MLT to multiply saidcoefficient by the character width information supplied from the memoryROM1', thus reducing the advancing amount of the printing ribbon IRcompared to the case of wheel 10K.

In this manner a memory of a large capacity can be dispensed with bystoring the information for a determined wheel, for example 10K, alonein the memory ROM1' and by employing a memory ROM2 for storingcoefficients for different wheels 12K, 15K, etc. and a multiplier MLT.

As explained in the foregoing, the present embodiment, utilizing theinformation of printing pitch obtained from means for proportionalspacing mode, allows reduction of the consumption of the single-useprinting ribbon IR thus achieving maximum economy in the utilization ofribbon IR.

FIG. 13 shows part of the bail start motor drive unit 122 and thecarriage indicator drive unit 124 shown in FIG. 7. Upon actuation of thepitch selecting key 10d provided in the keyboard 10 in FIG. 2, thecorresponding data are supplied through the keyboard control unit 24 tothe MPU 44, thereby storing a signal for activating one of thelight-emitting diodes 12a-12c in the latch 123 under the control of theaddress decoder 45. As an example, the key 10d is actuated once for themode of 10 characters per inch to light the LED 12a through the inverter200 thereby indicating the gradation 8a, then is actuated again to lightthe LED 12b through the inverter 201 thereby indicating the gradation 8bfor 12 characters per inch, and is actuated once again to light the LED12c through the inverter 202 thereby indicating the gradation 8c for 15characters per inch. Also the printer control unit 16 controls thecarriage driving motor 18 so as to cause the displacement of thecarriage 26 according to the thus selected printing pitch. The lightedLED, being mounted on said carriage 26, also serves to indicate thecarriage position. Also in response to each actuation of the key 10d,one of light-emitting diodes La, Lb, or Lc is lighted in a display unitL1 in the keyboard 10 to indicate which printing pitch is selected, 10characters, 12 characters, or 15 characters per inch, respectively.

As explained in the foregoing, the present embodiment, being providedwith plural indicating means La, Lb, Lc for different printing pitches,activates one of said indicating means La, Lb, Lc corresponding to theselected print pitch, thereby allowing the operator to easily confirmthe printing pitch on a scale indicated by said indicating means La, Lb,Lc, as well as the print position or the number of characters that canbe printed.

FIG. 14 shows part of the detecting unit 116 and part of the bail startmotor drive unit 122 shown in FIG. 7. A transistor 206 is provided todrive a paper bail start DC motor 207 to which a paper bail 250 (FIG. 2)and a microswitch 208 (FIG. 14) are linked. Thus, in response to aninstruction for the automatic loading of the printing sheet from thekeyboard 10, the transistor 206 is activated through the latch 123 todrive the DC motor 207, which releases the paper bail 250 from theplaten 17 and subsequently closes the microswitch 208. A bus driver 115receives a signal when the microswitch 208 is closed and also receives asignal through a single-input AND gate 210 from the detector 40 in thepresence of a reflecting plate 41. In response to the microswitchfunction detected through the bus driver 115, the MPU' 110 sets a numberdetermined by the MPU 44 in the counter 172 in FIG. 8 and drives thepaper feeding stepping motor 14 until the counter 172 reaches the zerocount state. Thereafter the paper bail 250 again comes into contact withthe printing sheet, and microswitch 208 is opened. In response to saidopening the MPU' 110 turns off the transistor 206 through the latch 123thereby stopping the DC motor 207.

FIG. 15 shows the details of the alarm control unit 49 shown in FIG. 6-2wherein provided are oscillators 220, 221 oscillating at mutuallydifferent frequencies f1 and f2; a monostable multivibrator 222 fordetermining the duration of the sound alarm in response to the signalSELBZ; a latch 229 for supplying the output signal of the oscillator 220or 221 to the loud speaker 42 through AND gates 223, 224 and OR gate 225under the control of the MPU 44; an inverter 226 to ensure that at mostone AND gate 223, 224 is open; and a filter 227 for modulating thesquare waves from the gate 225 to a pleasant waveform for supply to saidloud speaker 42 through an amplifier 228.

As explained in the foregoing, the present embodiment is provided withcounting means in various control units for controlling the printingpressure, amount of ribbon advancement, amount of sheet feeding, etc.according to the characters to be printed, and, the digital control ofthe apparatus is facilitated in this manner.

Now reference is made to FIG. 16 showing the details of the typeselecting motor control unit 117 (FIG. 7) for the type selecting motor29, wherein provided are a latch 130 for storing key informationsupplied from the MPU 44 to the MPU' 110 and converted into thepositional information on the typefont wheel 30 by the aforementionedcharacter position table 125; adder/subtracters 131, 133; a zerodetecting circuit 132; a digital-to-analog (D/A) converter 134 forconverting the digital result of calculation by adder/subtracter 133into a voltage; a power amplifier 135; a type selecting motor 29 ofwhich the shaft 29a is directly connected to the typefont wheel 30 (notshown) and a slitted disk 137 constituting an encoder 35. Across saiddisk 137 there are provided LEDs 147 and phototransistors 138, 139, and140, in which the phototransistors 138 and 139 are so positioned as toprovide signals of a phase difference of 90° while the phototransistor140 is so positioned as to provide an index output signal for each turnof the motor 29. Based on the signals from said phototransistors 138,139 a pulse generating circuit 141 generates a signal I for identifyingthe rotating direction and a signal H giving a pulse for each rotationcorresponding to a character.

An adding and subtracting counter 144 adds or subtracts, according tothe signal I, the count for each signal H, and the counter 144 is resetupon receipt of a signal F. In this manner the count of the counter 144indicates the rotation angle of the slitted disk 137 or the typefontwheel 30 with respect to a determined position of said disk 137.

An interval counter 142 counts the time interval of the pulses H' fromthe circuit 141, and the obtained count, being inversely proportional tothe rotating speed of the motor 29, is converted by an inverse numbertable 143 to a value proportional to the speed.

A servo control is obtained by calculating the positional error in theadder/subtracter 131, then subtracting the speed obtained from theinverse number table 143 from the above-mentioned positional error, anddriving the motor 29 according to the thus obtained difference. Thecircuit 132 for detecting zero positional error transmits the zerodetection to the MPU' 110 through the bus driver 115 and simultaneouslychanges over a switch 146 from the side of the D/A converter 134 to theside of a circuit 145 for forming a signal in the interval betweenslits. Said circuit 145 is composed of a resistor RA for passing thesubstantially sinusoidal signal from the phototransistor 138 in parallelwith a serial circuit comprising a condenser C and a resistor R forpassing said sinusoidal signal and a second resistor RD in parallel withan amplifier A. Thus, after the MPU' 110 detects the zero error signaldetected by the zero detecting circuit 132, the wheel 30 is stopped bythe circuit 145 and the printing hammer 32 is activated to perform theprinting. In this manner it is rendered possible to provide a preferableservo control process in which the wheel 30 can be stopped exactly andrapidly at the destination with the extremely simple and inexpensivestructure explained above.

FIG. 17 shows the details of the carriage driving motor control unit 118for the carriage driving motor 18 shown in FIG. 7, having a servocontrol structure similar to that employed in the type selecting motor29.

The MPU 44 transfers, to the MPU' 110, the instruction on the relativeamount of displacement and direction from the present location of thecarriage 26. The MPU' 110 adds or subtracts the relative amount to orfrom the present location according to the direction of displacement andtransfers the obtained destination to a latch 151. The latched value andthe output from an adding and subtracting counter 164 obtained accordingto the signal from a pulse generating circuit 161 are subjected to theaddition or subtraction in an adder/subtracter 152 to obtain apositional error. An adder/subtracter 154 subtracts the speed of thecarriage driving motor 18 obtained through a counter 162 and an inversenumber table 163 from said positional error, thus achieving a servocontrol of the motor 18 through a D/A converter 155 and an amplifier156. Upon zero detection by the zero detecting circuit 153, a switch 166is changed over to stop the carriage displacement in a similar manner asexplained in the foregoing. Signals similar to the foregoing areobtained from LEDs 167 and phototransistors 159, 160 positioned across aslitted disk 158 mounted on the shaft 18a of said motor 18. In thiscase, however, a counter 164 receives a limit signal obtained from anelement 168 comprising an LED and a phototransistor indicating theleft-hand end of the carriage displacement, instead of the index signalF generated at each turn in the case of the type selecting motor 29.Also a circuit 165 similar to the circuit 145 is provided.

FIG. 18 shows the manner in which FIGS. 18-1 and 18-2 should bearranged. Now reference is made to FIGS. 18-1 and 18-2 showing key inputdevices allowing rapid and secure key entries and adapted for use in anelectronic typewriter.

In the conventional key input device there is generally employed amethod of accepting the key input information only after the key signalis stablized or plural readings of the key signal have resulted in asame result. For this reason a rapid key information entry is difficult.

Also in case a key signal during the course of stabilization isinterrupted for some reason, the apparatus may regard that the key hasbeen actuated twice despite the fact that the key was actuated onlyonce.

The embodiment shown in FIGS. 18-1 and 18-2 provides key input devicesnot associated with the above-mentioned drawbacks and allowing rapid andaccurate key entries with a simple structure.

In FIGS. 18-1 and 18-2 groups of addressable latches 60 are providedwith memory cells or latches L11-Lnn respectively corresponding to thelattice points S11-Snn of a key matrix 88 of the keyboard 10. Saidlattice points S11-Snn of said key matrix 88 correspond to the inputkeys shown in FIG. 1, including not only the unlocking keys such ascharacter keys 10a, control keys 10b and 10c, but also the locking slidekeys 10e and 10f. Each of the latches L11-Lnn, corresponding to eachkey, has a structure of 2 bits constituting a memory for storing the keysignal. All the latches L11-Lnn of the addressable latch group 60 arereset to "0" at the turning on of the power supply unit 13.

Each key switch 88a of the key matrix 88 is provided with a diode 88b inorder to avoid stray signals in case plural keys are actuatedsimultaneously. In the following discussion, the key switches 88a willbe designated as switches SW11-Swnn at corresponding lattice points.

There are shown also a decrementer 61; a logic circuit 59 composed ofinverters 81, 82 and an AND gate 83 for zero detection of the signalread from the group of latches 60, providing a signal "1" from said ANDgate 83 upon such zero detection; and AND gates 78, 79, 75, and 76 andOR gates 80 and 77 for resetting said group of latches 60.

An oscillator 66 generates synchronizing clock pulses for various unitsand basic signals for scanning the key matrix 88 and the LED matrix 89.The signals from said oscillator 66 are supplied through an AND gate 73to a counter 65 so constructed as to repeat counting of the number ofthe lattice points S11-Snn of the matrix 88. The counter 65 counts thesignals from said oscillator 66, and the output signals on said counter65 are utilized as the addressing signals for the addressable group oflatches 60 and also divided into the upper-digit signals and lower-digitsignals which are respectively supplied to a decoder 62, which may be,for example, part number 74154 supplied by the Texas Instruments Corp.,and to a multiplexer 63. The microprocessing unit 44 is capable ofsensing the content of said counter 65 any time through a bus driver 86and a data bus DB. Said decoder 62 scans the key matrix 88 in thelateral direction with the increment of the counter 65, while themultiplexer 63 vertically scans the matrix 88 during one stepadvancement of the decoder 62.

If a key switch 88a is found closed during the vertical scanning, switchSW34 for example, the multiplexer 63 provides an output signal "0",which is inverted by an inverter 74 into "1" and supplied to the ANDgates 76, 79, and 84 in order to show the content of the counter 65 atthis point. At this state the latch L34 corresponding to the closed keyswitch SW34 releases an output "0" whereby the gate 83 provides anoutput signal "1" to the AND gate 84. Thus said gate 84 provides anoutput signal "1" which is supplied as an interruption signal INT to theMPU 44. At the same time the reset output signal F="1" of a flip-flop 71already reset and the output signal "1" of the AND gate 84 are suppliedto a NAND gate 72 to provide an output signal "0", whereby an input ANDgate 73 for the counter 65 is closed to terminate the counting functionof the counter 65 at a count corresponding to the closed key switchSW34. Also the output signal "0" from the multiplexer 63 retains the ANDgates 75 and 78 closed but opens the AND gates 76 and 79 thereby causingthe OR gates 77 and 80 to provide output signals "1", which are used asthe input signals for the latch address by the counter 65 correspondingto the closed key switch SW34. The group of latches 60 are so structuredas to latch the input signal in synchronization with the output signalfrom the input AND gate 73 for the counter 65, so that the latch addressis not changed but remains corresponding to the closed key switch SW34while the function of the counter 65 is stopped. In response to theaforementioned interruption signal INT, the MPU 44 reads the count ofthe counter 65 through the bus driver 86 to identify the closed keyswitch SW34, thus accepting the input information from key S34.Thereafter the MPU 44 releases an acknowledging signal "1" to the setinput port of a flip-flop 71 through the address bus AB and a decoder 87to release a set output signal F="0" from said flip-flop 71, whereby aNAND gate 72 provides an output signal "1" to open the gate 73, thusre-starting the counting action of the counter 65. Simultaneously theoutput signal from said gate 73 sets "11" in binary code, or "3" indecimal code, in the latch L34 corresponding to the closed key switchSW34. In response to the re-start of counting by the counter 65, theflip-flop 71 is reset for the next key detection.

In case said key switch SW34 is still closed after the scanning of allthe lattice points Sll-Snn of the key matrix 88 (this situation isnormally encountered in the usually employed scanning speed), themultiplexer 63 again provides an output "0", but the corresponding latchL34 provides an output "3" to give output signals "0" from the gates 83and 84, whereby the interruption signal INT is given to the MPU 44 andthe AND gate 73 is closed. Consequently, the counter 65 continues thecounting operation as if the key switch SW34 were not closed. However,since the AND gates 75 and 78 are closed by the output signal "0" fromthe multiplexer 63, a signal "3" is again set in the latch L34corresponding to the closed key switch SW34 through the AND gates 76, 79and OR gates 77, 80. In this manner the signal "3" is repeatedly set insaid latch L34 while the corresponding key switch SW34 is closed. Then,when said key switch SW34 is opened, the multiplexer 63 provides anoutput signal "1" at each scanning to close the AND gates 76, 79 and toopen the AND gates 75, 78 through the inverter 74, whereby a numberstep-decreased by the decrementer 61 is set in said latch L34 throughthe OR gates 77 and 80. In this manner the content of said latch L34changes from "3" to "0" in succession. When said latch L34 finallyreleases an output signal "0", the AND gate 83 of the zero detectioncircuit 59 provides an output "1", which is converted to "0" by aninverter 85 and closes also the AND gates 75 and 78. Thus the OR gates77, 80 release output signals "0" to set said latch L34 and all otherlatches L11-Lnn to "0" in response to the counting operation of thecounter 65.

FIGS. 19A, 19B-1 and 19B-2 show the various signals when a key S34 isactuated in a 4×4 key matrix. FIG. 19B shows the manner in which FIGS.19B-1 and 19B-2 should be arranged. In FIGS. 19B-1 and 19B-2, Trepresents the duration of the actuation of the key S34 as identified bythe circuit.

As explained in the foregoing, the present key input device is sostructured as to accept the key signal at the first scanning after thekey switch is actuated and not to accept said key signal in thesucceeding scannings by the output of the latch storing the key signaland is therefore capable of rapid signal reading, since even an unstablekey signal is accepted at the first scanning and is not acceptedthereafter.

Also the present key entry system, accepting the key signal only at thefirst scanning, allows to use the key matrix not only for momentary keysbut also for locking slide keys such as the keys 10e, 10f shown inFIG. 1. For the same reason, the so-called N-key roll over method iseasily applicable.

The key signals entered in this manner by the key actuations areprocessed by the MPU 44 and supplied to the printer control unit 16 forperforming the determined printing operation.

As shown in FIG. 18-2 a circuit is provided for displaying the actuatedinput keys S11-Snn with light-emitting diodes D11-Dnn, wherein providedis a cathode driver 64 for dynamic driving of the light-emitting diodesDll-Dnn in an LED matrix 89 in response to the output from the decoder62. A multiplexer 67 receives the upper digit signals which are the sameas those supplied to the decoder 62 from the counter 65 and an addressbus AB for supplying the display information from the MPU 44 to adisplay buffer 68. The lighting operation is achieved by reading thecontent of an address in the buffer 68 corresponding to the count ofsaid counter 65, storing said content in a latch circuit 69 and drivingan anode driver 70 accordingly. Also a change in the lighting state isachieved by designating the buffer 68 by the decoder 87, whereby themultiplexer 67 connects the address bus AB to the buffer 68, and bydesignating the changed address from the address bus AB to transfer thechanged data from the data bus DB to said buffer 68.

It is to be noted that the present embodiment is capable of allowingvarious functions not achievable with the conventional typewriters. Inthe following are explained such functions of which usefulness will bemade evident from the corresponding key manipulations. Even the ordinarykeys found in usual typewriters can perform unique functions when usedin combination with certain keys belonging to the present embodiment. Inthe following the functions and operating procedure of the keys areexplained first, and the control process relating to particular keys forspecific functions will then be explained. In this manner the electronictypewriter of the present embodiment will be further clarified.

FIG. 20 shows, in a front view, the control panel of the electronictypewriter of the present embodiment, wherein one of the mode keys 10dis labeled PITCH and designates the number of characters per inch asexplained in the foregoing. Upon actuation of said PITCH key the displayin a display unit L1, composed for example of light-emitting diodes La,Lb, Lc, Ld, is shifted cyclically in the order of "10", "12", "15", andPS", in which PS stands for proportional spacing with a variable numberof characters per inch according to the characters printed. Another ofthe mode keys 10d is labeled LINE SPACE and selects the amount of theline space wherein 1/6 inch is taken as the unit amount. Similarly, theportions labeled "3/4", "1", "11/2", and "2" in the display unit L2 arecyclically lighted in turn upon actuation of said LINE SPACE key. Stillanother of the mode keys 10d is labeled KB SELECT and is utilized forselecting a character in a key 10a representing three characters, forexample, a key KIII. In the present embodiment the lamp I in the displayunit L3 indicates the characters " " and "§" which are furtherselectable by the control key 10b labeled SHIFT, while the lamp IIindicates the character "|". Either of said lamps I and II is lighted byactuating the KB SELECT key.

One of the mode keys 10g is labeled FM CONTROL and selects one of threefunction codes JUST, AUTO, and OFF as indicated by the lamps of thedisplay unit L4. The lamp JUST indicates a function of "rightjustification" in which right-hand ends of the lines are aligned, whilea lamp AUTO indicates a function of automatic line feeding. A lamp OFFindicates no particular function instructed. Another of the mode keys10g is labeled OP CONTROL and is utilized for determining the outputprinting mode of the electronic typewriter, wherein the lamps C, W, L,and STORE are cyclically lighted in the aforementioned manner. C, W, andL respectively indicate the printing by a character, by a word, and by aline, and STORE means the storage in an internal memory 54, in which theline printing mode L is employed.

A locking slide key 10e is designated in this embodiment as key SSW1 andis related to the decimal tabulator function for figures. It selectsprinting of figures in 3-digit groups separated by a space whenpositioned at "SP", or printing of figures in 3-digit groups separatedby a comma when positioned at ",", or printing of figures without suchgrouping when positioned at "XX". A locking slide key 10f is designatedin this embodiment as key SSW2 and selects the kind of type orunderlined printing. "X₋₋ X" stands for boldfaced type with a continuousunderline, "X X" for boldfaced type with an underline for each word,"XXX" for boldfaced type, "Y₋₋ Y" for ordinary type with a continuousunderline, "Y Y" for ordinary type with an underline for each word, and"YYY" for ordinary type. There are also provided control keys 10bincluding keys labeled DECTAB for instructing the decimal tabulatorfunction; LAYOUT with a lamp for instructing the column layout function;INDENT with a lamp for instructing an automatic indent mode; FORMAT witha lamp for giving instructions on page formatting; MAR REL for releasingleft and right margins; MEMORY for initiating storage in the memory 54;NONPRT for reviewing the sentence memory; and REPEAT for repeatedprinting or entry of a character. Further provided are keys 10b labeledSHIFT for entering upper case characters or for certain specialfunctions in combination with other keys; LOCK for locking said SHIFTkey; BACK TRACE for correction of printing involving preceding lines;and TAB for advancing the carriage 26 to the next tabulator stopposition. Also provided are control keys 10c including keys labeled BACKSPACE for shifting the printing position toward the left; X for erasinga character; INDEX for line feed of the printing sheet; REV INDEX forreverse line feed of the printing sheet; CODE with a lamp for specialinstructions in combination with other keys; CENT with a lamp forcentering of the printing; for interrupting the printing; LM for settingthe left margin position; RM for setting the right margin position; SETfor setting the tabulator stop positions; CLR for clearing the tabulatorstop positions; RELOC for displacing the carriage 26 to the last printedposition; and ← and → for moving the cursor on the display unit 9; aswell as a second SHIFT key.

Surrounded by the broken line are character keys 10a, including keyslabeled SPACE for shifting the carriage 26 towards the right for makinga space and RETURN for returning the carriage 26 to the left-endposition and line feeding the printing sheet.

FIG. 21 shows the internal structure of the flag group 50 shown in FIG.6-2, wherein provided are the following flags.

A flag KB2 is set when the KB SELECT key is set to mode II to enable thekey KIII to print "|" and is reset when the KB SELECT key is set to modeI. An INDENT flag is set at the start of the automatic indent mode inwhich the carriage 26 is always returned to a temporary left-hand marginstop position and is reset when said automatic indent mode is cancelled.An STR flag is set when the OP CONTROL key selects the mode STORE and isreset at the selection of any other mode. A flag TR is set at the inputof a title followed by the actuation of the RETURN key for the purposeof referring to a character row and is reset when said reference iscancelled. A flag NP is set when the NONPRT is actuated and is resetwhen the reference to the character row is cancelled. A flag SCindicating the entry of a character row for searching is set upon entryof the character row for reference and is reset when the reference tothe character row is cancelled. A flag CMV is set when one of fourcentering modes is established and is reset when the centering mode iscancelled. A flag TCNT is set when a centering mode between tabulatorstop positions is instructed, a flag MCNT is set when a centering modebetween the margin stop positions is instructed, a flag PCNT is set whena centering mode between designated positions is instructed, and a flagWCNT is set when a centering mode between words is instructed. FlagsTCNT, MCNT, PCNT, and WCNT are reset when the corresponding centeringmode is cancelled.

FIG. 22 shows the internal structure of the register group 51 shown inFIG. 6-2. A register LEPT indicates the last position of the charactersstored in the line buffer 52. A register PRTEPT indicates the print endpoint in the characters stored in the line buffer 52. A register CRGPTindicates the position of the carriage 26 from the left margin stopposition on the printing sheet, thus representing the displacingdistance of the carriage 26 from said position. A register DCRGPT storesthe amount of displacement to be performed by the carriage 26 in theword-unit (W-mode) or line-unit (L-mode) printing mode in which thecarriage 26 is not displaced immediately after the entry of key signals.A register PITCH stores the printing pitch information selected by thePITCH key, so that the MPU 44 can read the printing pitch from saidregister PITCH. A register LNSP stores the amount of line feed or theselection state of the LINE SPACE key. Registers FMC and OPCONTrespectively store the states of the FM CONTROL key and the OP CONTROLkey. Registers LM and RM store the left and right margin stop positionsin the same unit as in the register CRGPT. Registers SSW1 and SSW2 storethe state of the keys SSW1 and SSW2 on the control panel. A register DLMis utilized for diverting the left margin stop position in case of theautomatic indentation mode.

Also registers TABl to TABn respectively store the tabulator stoppositions in the same unit as in the register LM. A register WORK isutilized for temporary storage or diversion of the information duringother control processes. A register CPT is utilized in the correctionprocess and indicates a point in the line buffer 52 corresponding to thecarriage position. This register WORK stores the data of printedcharacters and associated printing pitch, etc. and supplies, when acorrection is needed, said data to the MPU 44 from the older data to thenewer data in the same manner as in a first-in-first-out stack toinversely reproduce the displacement of the carriage 26 and theadvancement of the printing sheet, thus allowing the carriage 26 toreach the final character position of the previously printed line. Alsoa register LC stores the number of lines advanced on the printing sheet.

FIG. 23 shows the internal structure of the line buffer 52 shown in FIG.6-2 having unit memories from 0 to n. In each unit memory, the addressesI, II, and III respectively store the kind of character, the printingpitch, and the kind of type which are utilized for the correctionprocess and other purposes. The data stored in the address I are thecharacter key information supplied from the keyboard control unit 24shown in FIG. 6-1. The data stored in the address II represent theprinting pitch corresponding to the state of the PITCH key or to thecontent of the PITCH register. The data stored in the address IIIrepresent the kind of type corresponding to the state of the slideswitch SSW2 shown in FIG. 20 or the content of the register SSW2 in theregister group 51. The capacity of the line buffer 52 is so selectedthat it can store a number of characters in excess of the maximum numberof characters in a line, for example 300 characters over 2 lines. Thusby actuation of the BACK SPACE key the carriage 26 can be returned fromthe left-hand end position to the final print position of the precedingline. Stated differently, such final print position of the precedingline can be calculated from the carriage displacing instruction,distance of carriage displacement, and amount of line feed, all storedin said line buffer 52. Even when said preceding line is printed with ablank space at the left-hand end of the line, a memory area of the linebuffer 52 preceding to the first character in said line stores a codecorresponding to a space in the address I, a printing pitch in theaddress II, and a non-print code in the address III as the kind of type,so that the displacement of the carriage 26 to the final print positionof the preceding line is made possible by decoding the thus stored databy the MPU 44 in an order opposite to that in the data entry.

In the system as explained in the foregoing, the control sequence isinitiated at the turning on of the power supply unit 13 to theelectronic typewriter. Immediately after the start of power supply, thecontrol units 24, 16, 48, 49, etc. shown in FIGS. 6-1 and 6-2 areinitialized. Then the register group 51, line buffer 52, and flag group50 are cleared. Subsequently, in order to restore the state beforeinterruption, the data of the entire register group 51 stored in anon-volatile memory 57 shown in FIGS. 6-1 and 6-2 are recalled to theregister group 51. At the same time, according to the states of variousregisters, the lamps for the PITCH, LINE SPACE, FM CONTROL, and OPCONTROL keys are controlled and the carriage indicator lamp 12 islighted. Similarly the lamp of the KB SELECT key is controlled by thestate of the KB2 register stored in the secondary memory 57.

In this manner it is possible to restore the state immediately beforethe interruption even when the power supply unit 13 is turned off orinterrupted by a line failure. Then in response to the actuation of akey, 10a-10g, there is initiated a key discriminating sequence fordistinguishing character keys 10a from control keys 10b, 10c. Saiddiscrimination is achieved by the value of the key signals. Thecharacter keys 10a are distributed continuously on the key matrix 88shown in FIGS. 18-1 and 18-2, and the control keys 10b, 10c aresimilarly distributed continuously, so that there results a boundaryvalue between the group of character keys 10a and the group of thecontrol keys 10b, 10c. Consequently, it is rendered possible todiscriminate a key 10a-10g by comparing the corresponding key signalwith said boundary value. In case a character key 10a is identified,there is executed a process on the line buffer 52. As shown in FIG. 20,the SPACE and RETURN keys are considered to belong to the character keys10a. On the other hand, in case a control key 10b, 10c is found, saidcontrol key 10b, 10c is further identified and a corresponding controlsequence is executed.

FIGS. 24 and 25 show the basic control sequences of the line bufferstorage process LBFSTR. In the LBFSTR sequence shown in FIG. 24, inresponse to the entry of the kind of character, printing pitch, and kindof type from a character key 10a to the line buffer (LB) 52, theregisters LEPT and DCRGPT are step increased. Then the LBFSTR sequenceis branched according to the content of the register OPCONT shown inFIG. 22. In case the register OPCONT indicates C-mode or character-unitprinting, there is immediately initiated a print sequence BFPRT withconsecutive display on the display unit 9. In the case of W-mode(word-unit printing), the entered key is identified if it is the SPACEor RETURN key, and, if it is not, the consecutive display alone is givenwithout printing. In the case of L-mode (line-unit printing), theentered key is identified if it is the RETURN key, and, if it is not,the consecutive display alone is given without printing. In theword-unit printing mode the printing is initiated upon actuation of theRETURN or SPACE key, while in the line-unit printing mode the printingis initiated upon actuation of the RETURN key. In this manner isachieved character-unit printing and display, word-unit printing anddisplay, or line-unit printing and display.

In case a new character is entered after the line buffer (LB) 52 isfilled with the kind of character, printing pitch, and kind of type overthe entire memory areas 0-n, the stored data are shifted three steps tothe left and the contents of registers LEPT and PRTEPT are step reduced.In this manner the three data stored in the 0th area at the left-handend of the buffer memory 52 are removed and the nth right-hand endmemory area is emptied to accept the kind of character, printing pitch,and kind of type for the (n+1)th character. Also in response to theactuation of the SPACE or RETURN key, the related data are successivelystored in the line buffer 52 as shown in FIG. 23, so that the correctionof characters is possible as long as they are stored in said line buffer52. Since the data for the SPACE or RETURN key are in this manner storedas character information together with the associated printing pitch andnon-print information, it is possible to make corrections by tracing theprint backward in any mode of printing.

The buffer printing (BFPRT) process is conducted according to the printcontrol sequence BFPRT shown in FIG. 25. In said BFPRT sequence thecontents of the registers LEPT and PRTEPT are compared, and, if they aremutually different, a character is printed and the registers PRTEPT andCRGPT are both step increased. This sequence is repeated until thecontents of the registers LEPT and PRTEPT become mutually equal. In thismanner said sequence BFPRT performs the printing of unprinted charactersstored in the buffer 52. Upon completion of said sequence BFPRT, thecontents of the registers PRTEPT and LEPT are mutually the same, and thecontents of the registers CRGPT and DCRGPT are also mutually the same.

The procedures of storage of a character row or a sentence and ofdisplay and printing from such stored sentence will now be explained.

The key operations for the write-in of a character row or a sentenceinto the sentence memory 54 are conducted as shown in FIG. 26.

At first the OP CONTROL key is actuated to light the STORE lamp. Thenthe MEMORY key is actuated to light the MEMORY key lamp, thus indicatinga state for sentence storage. Then entered are the characters for thetitle name, which are displayed on the display unit 9, followed by theactuation of the RETURN key, whereby the printing of the thus enteredtitle name, the return of the carriage 26, and the line feed of theprinting sheet are executed. At this point an alarm is given fromloudspeaker 42 if the entered title name already exists. Thereafter areentered the characters to be stored, and the RETURN key is actuated toprint and store said characters. Upon actuation of the MEMORY key, thetitle name is recorded in association with the entered characters andthe MEMORY key lamp is extinguished. The key, if actuated during theentry of characters, will function as a temporary stop signal in theprinting of the characters recalled from the memory 54.

In the following the process of character storage is explained.

In FIG. 27, the MPU 44 shown in FIG. 6-1 lights the MEMORY key lamp inresponse to the first actuation of the MEMORY key, and checks theregister STR of the register group 50 to see if the storage (STR=1) orreadout (STR=0) of characters is requested. Said flag STR is set by theactuation of the OP CONTROL key to the STORE mode. In case of thecharacter readout the program proceeds to the memory readout controlsequence MRD shown in FIGS. 29-1 and 29-2. In case of character storage,the program proceeds to the next KEY INT step for awaiting keyactuation, and, since the MEMORY or RETURN key is not yet actuated inthis state, the program further proceeds to the next character entrystep. In response to the key entry of the title name, the aforementionedbuffer process routine LBFSTR shown in FIG. 22 is executed to store thecharacters in succession into the line buffer 52, with simultaneousdisplay on the display unit 9. Upon completion of the entry of the titlename, the RETURN key is actuated as shown in FIG. 26, and the program inFIG. 27 proceeds to the branch from the step "RETURN?". Then checked isthe state of the flag TR. Since said flag TR is reset in the initialstate, the program proceeds to the buffer printing routine BFPRT forprinting the title name. Then the flag TR is set, the title name in theline buffer (LB) 52 is diverted into the WORK register, and the titlename thus diverted is compared in the MPU 44 with all the title namesstored in the sentence memory 54.

If the same title name is already registered in the sentence memory 54,an acoustic alarm is generated from the loudspeaker 42, and the MEMORYkey lamp is extinguished.

If the same title name does not exist, the program awaits the followingkey entry at the KEY INT step. The title name in the line buffer 52 isextinguished when it is diverted into the WORK register, but the displayof the title name on the display unit 9 is continued since the titlename in said WORK register is supplied to the display control unit 48.

Also in response to the actuation of the RETURN key, the printing sheethaving the printed title name is advanced by a line, and the carriage 26is returned to the left margin stop position.

At this point the carriage return command, distance of carriagedisplacement from the left-end position, and amount of line feed arestored in the line buffer 52 in the order of key actuations as shown inFIG. 23.

Also in the carriage advancement without printing by the actuation ofthe SPACE key, the data for space, printing pitch, and non-printinformation are stored as shown in FIG. 23. Such data relating to theprinting are serially transferred, together with the data for title nameand characters, to the WORK register and the sentence memory 54. Also inthe readout from the memory 54 for display or printing, said data areeliminated and the character information alone are displayed and/orprinted.

Upon entry of characters for storage, the program proceeds to thesequence LBFSTR according to which the characters are sequentiallystored in the line buffer 52 and displayed in succession on the displayunit 9. Upon actuation of the RETURN key after the entry of a characterrow or a sentence, since the flag TR is set in this state, thecharacters in the line buffer 52 are stored in the sentence memory 54,and the program again enters the sequence LBFSTR and proceeds to thesequence BFPRT for printing the characters.

Succeeding storage of the sentence is achieved by the repetition of theabove-mentioned procedure. During this operation, the content of theline buffer 52 is not cleared but is extinguished from the leading endonly in case of overflow, and this process is effective for permittinguse of the character correction process as explained in the foregoing.

In response to the actuation of the MEMORY key at the end of the entryof characters, the title name is registered in association with the thusentered characters. At the same time, the MEMORY lamp is extinguishedand the flags STR and TR are reset.

FIG. 28 shows the manner in which FIGS. 28-1 and 28-2 should bearranged. Now reference is made to FIGS. 28-1 and 28-2 showing the keyoperations in the display and printing of the characters read from thememory 54.

At first the OP CONTROL key is actuated to turn off the STORE lamp. Thenactuated is the MEMORY key, whereby the MEMORY key lamp is lighted toindicate the stand-by state for the display and printing of charactersread from the memory 54. The display or printing is selected by theoperator. In case of display the NONPRT key is actuated, whereby thecorresponding NONPRT key lamp is lighted to indicate that the displaymode for the characters read from the memory 54 is initiated.

In said mode, first entered is the title name, which should naturally bethe same as the registered title name. Then, in case of display from aparticular character row in the sentence, the operator performs theactuation of the key, entry of said particular character row, and theactuation of the RETURN key. Also, in case of the display from the startof said sentence, the operator merely actuates the RETURN key followingthe entry of the title.

Upon actuation of the RETURN key there are displayed for example 20characters from the beginning of the sentence. At this state the cursorposition on the display unit 9 can be displaced by word units with the ←or → key, and deletion, insertion, etc. is made possible by the BACKSPACE and X keys. The display is terminated by the actuation of theMEMORY key. Also the entire display of characters can be deleted by theactuation of the key CLR while said characters are displayed on thedisplay unit 9. Upon actuation of the MEMORY or CLR key, the NONPRT andthe MEMORY key lamp are extinguished.

The printing of stored characters can be achieved in at least in threeforms, i.e., the printing of the entire sentence without title, theprinting of the entire sentence with title, or the printing of the firsttwo lines of said sentence with title. These printing forms arerespectively achieved by the entry of the title name, followed by theentry of "/0", "/1", or "/2" further followed by the actuation of theRETURN key. Also the entry of "/0" may be omitted in the first form. Theprinting is initiated immediately after the RETURN key is pressed. Alsoas explained in the foregoing, the printing can be temporallyinterrupted at a position of the key entered in the course of characterentry. Also the printing can be interrupted at any point by theactuation of the key during the course of printing. After the completionof printing of a sentence corresponding to a title name, said printingcan be repeated by simply actuating the RETURN key. Also by actuating"/2" without title name in the third form, there are printed all theregistered title names respectively accompanied by two lines ofsentence. The present mode can be terminated by actuating the MEMORYkey, whereupon the MEMORY key lamp is turned off to indicate thetermination of said mode. In the following are explained the internalfunctions corresponding to the above-mentioned key operations.

As explained in the foregoing, the memory readout sequence MRD isinitiated in case of the flag STR=0 in FIG. 27. The sequence MRD startsfrom a key actuation waiting step KEY INT, and the entered key signal isthereafter indentified.

As shown in FIGS. 28-1 and 28-2 the operator determines whether thesentence readout is made on the display unit 9 or by the printing unit43.

By actuating the NONPRT key followed by the entry of the title name, thesentence stored in the sentence memory 54 is displayed on the displayunit 9.

Also the entry of the title name without actuating the NONPRT keyprovides the printing of said sentence on the printing sheet by theprinting unit 43. In this manner the stored sentence can be reproducedfor enabling the operator to identify if such stored sentence can beutilized for preparing a new sentence. Also correction can be easilymade on the display unit 9.

The sentence readout by printing is useful in making corrections, etc.because in the readout by display it is sometimes difficult for theoperator to understand the entire sentence because of the limitation inthe capacity of the display unit 9.

FIG. 29 shows the manner in which FIGS. 29-1 and 29-2 should bearranged. FIGS. 29-1 and 29-2 show the key operations in the memorysequence MRD.

In case of the readout by the display unit 9, the NONPRT key is actuatedto set the flag NP. Then the title name, for example "NO3" or "NEWYEAR'S CARD", of the sentence to be recalled is entered from thekeyboard 10.

Upon the entry of said title name, the program proceeds to theaforementioned line buffer storage process routine LBFSTR to store theentered title name in the line buffer 52 and to display said title nameon the display unit 9.

Then the operator confirms the title name displayed and actuates theRETURN key.

The program checks the state of the flag TR, which is reset in theinitial state, and sets said flag TR.

Then the title name stored in the line buffer 52 is diverted into theWORK register to continue the display, and said line buffer 52 iscleared. Since the flag NP is already set by the actuation of the RETURNkey, the display unit 9 displays the sentence corresponding to saidtitle name, by comparing the title name stored in the work memory 112with the title names in the sentence memory 54 in the MPU 44. Suchdisplay on the display unit 9, having for example a capacity of 20characters, allows the operator to approximately confirm if the storedsentence is usable for the purpose of the operator. Also the entiresentence corresponding to the title name displayed on the display unit 9can be erased by actuating he CLR key. In this operation the programproceeds in a step CLR? to the branch YES, then in a step TR=1? to thebranch YES since the flag TR is already set by the actuation of theRETURN key, and the title name and the corresponding sentence are allcleared from the sentence memory 54.

Also, during the display of the title name or the sentence on thedisplay unit 9, it is possible to delete or correct the words displayedby means of the ← or → key.

Furthermore, after the entry and display of the title name, it ispossible to cause the display of the sentence from the beginning thereofor from an interim position thereof. In this case the operator actuatesthe key, and the program checks the state of the flag TR. As TR=0 inthis state since the RETURN key has not been actuated, the program setssaid flag TR, then also sets the flag SC, diverts the displayed titlename to the WORK register, and clears the line buffer 52. However thedisplay of the title name is continued by the signal from the WORKregister. Then the characters for searching from an interim position ofthe sentence are entered and stored in the line buffer 52 according tothe aforementioned sequence LBFSTR with the simultaneous display on thedisplay unit 9. Upon actuation of the RETURN key, the program checks thestate of the flag TR, which is already set by the key, then proceeds ina step SC=1? to the YES branch as the flag SC is also set, and divertsthe character for search in the WORK register to continue the display.As the flag NP is set by the NONPRT key, the program further proceeds tothe YES branch to display the sentence from an interim position on thedisplay unit 9.

More specifically, in case the characters "NEW" for search are stored inthe WORK register, the MPU 44 searches the same characters from thebeginning of the sentence stored in the sentence memory 54, and displaysthe sentence following said same characters. In this manner it isrendered possible to rapidly locate the desired part of the sentence. Incase another part of the sentence starting from the same characters"NEW" is desired, the key is again actuated whereby the program goesthrough the steps TR=1? and SC=1?, then checks the state of the flag NPwhich is set in this state, and displays another part of the sentencealso starting from the characters "NEW". The above-mentioned procedureis also achievable with the printing unit 43, in which case the titlename is entered without actuating the NONPRT Key, and the key isactuated.

Thus, in the same manner as explained in the foregoing, the program setsthe flags TR and SC and diverts the title name in the buffer 52 into theWORK register for maintaining the display of the title name on thedisplay unit 9. Then, upon entry of the characters for search, thedisplay of the title name is replaced by said characters, and, upon theactuation of the RETURN key, said characters for search are divertedinto the WORK register and displayed because TR=1 and SC=1 in thisstate. Since the NONPRT key is not actuated in this state, the programproceeds in the step NP=1? to the NO branch to cause the printing unit43 to print a part of the sentence starting from said characters forsearch. During said printing the characters for search are maintained onthe display unit 9, so that the printing can be immediately interruptedby the key in case an error is found in the characters. Also, in thecase of merely recalling the stored sentence by the printing unit 43,the operator has the freedom of selecting one of three printing formsmentioned in the foregoing.

In the first printing form in which the entire sentence is printedwithout the title name, the keys "/", "0" and "RETURN" are actuated insuccession after the entry of the title name. Thus the program proceedsin the step TR=1? to the NO branch, since the flag TR is not set in thebeginning, then sets the flag TR and diverts the title name in the WORKregister. Then the program proceeds in the step NP=1? to the NO branch,as the flag NP is not set in this case, and the MPU 44 identifies thedata "/0" and executes the printing by supplying the entire sentence andthe related print data from the sentence memory 54 to the line buffer52. In this state the format at the sentence registration can be exactlyreproduced, since all the data such as space, carriage return, printingpitch, sheet line feed, etc. are stored in the sentence memory 54together with the character information.

In this manner, the registered sentence can be immediately utilized forthe preparation of a new sentence.

Also the display of the title name is maintained on the display unit 9during said printing without title name so that the printing can beinterrupted by the key in case an error in the title name or in the keyentries is discovered, thus allowing the operator to avoid waste in timeand in the printing sheet. Also, any number of copies can be prepared byrepeating the actuation of the RETURN key.

Also, in the second or third printing form, the MPU 44 identifies thedata "/2" or "/3" entered after the title name entry and causes theprinting of the entire sentence with title name or of two lines ofsentence with title name. The display of the title name on display unit9 is maintained also in these printing forms. Furthermore, in the firstor second printing form, the printing is automatically interrupted at apoint where the key is actuated in the course of the registration of thesentence.

The above-mentioned mode is terminated by the actuation of the MEMORYkey, whereby the MEMORY and NONPRT lamps are turned off. Also, if thetitle name entry is omitted in the third printing form, the MPU 44identifies the absence of title name at the diversion of the title nameinto the WORK register by the actuation of the RETURN key, and causesthe printing of all the title names stored in the sentence memory 54 andtwo lines of sentence respectively belonging to said title names, thusallowing rapid review of the registered information. The number of linesto be printed can be arbitrarily selected by a numeral key "2", "3",etc. actuated successive to the "/" key.

In the following the registration and readout of page formats areexplained. In case the entry points EP1-EP11 on the printing sheet P aredifferent from line to line as shown in FIG. 30, it is convenient ifthese entry points EP1-EP11 can all be registered and the carriage 26can be brought automatically to these entry points EP1-EP11 at theprinting and line feed. In order to meet such requirement the presentembodiment is further provided with the functions of registration andreadout of the page formats.

The registration of the page format is effected according the sequenceshown in FIG. 31, in which the OP CONTROL key is at first actuated tolight the STORE lamp. Then the FORMAT key is actuated to establish thepage format registration mode, whereupon the FORMAT key lamp is turnedon to indicate said mode. Then entered is the title name for the pageformat, which should start from a character in order to distinguish saidtitle name from that for the registration of the tabulator stoppositions to be explained later. The title name entry is terminated bythe actuation of the RETURN key. Thereafter the title name is printedand the printing sheet P is advanced by a line to indicate that theentered title name has been accepted. However, if the entered title namealready exists, there will be given an alarm in the same manner asexplained in the foregoing, and the entered title name is not accepted.The operator displaces the carriage 26 to the entry point EP1 in thefirst line by means of the SPACE key, etc., and actuates the key todesignate the entry point EP1. Upon completion of the registration ofthe entry points (EP1 only in the example shown in FIG. 30) in the firstline, the RETURN key is actuated to instruct the storage of all theentry points (EP1) in the first line, and this procedure is repeated forthe 2nd through nth lines (n=6 in the example shown in FIG. 30). Uponcompletion of the storage of the page format, the FORMAT key is actuatedto terminate the registration procedure, whereby the FORMAT key lamp isturned off to indicate that the entry reception is terminated. In theillustrated example there is a blank line between the entry points EP10and EP11, and such blank line can be obtained by actuating the RETURNkey without the key after the RETURN key is actuated following theregistration of EP10.

Now FIG. 32 shows the procedure of readout of the thus registered pageformat. In said procedure the OP CONTROL key is actuated at first toturn off the STORE lamp. Subsequently the FORMAT key is actuated,whereby the FORMAT key lamp is turned on in the same manner as in theregistration of the page format. Then the title name is entered, and theentry is completed by the actuation of the RETURN key. At this point theregistered page format is recalled so that the carriage 26 is shifted tothe next entry point EP1, EP2, etc. upon each actuation of the key. Thusa document of the form shown in FIG. 30 can be prepared by enteringcharacters following the actuation of the key. This mode is terminatedby the actuation of the FORMAT key, whereby the FORMAT key lamp isturned off.

In the following are explained the registration and readout of thetabulator stop positions. The tabulator stop positions, for example setat EP6, EP9 and EP7, EP10 in the format shown in FIG. 30, are cancelledwhen the tabulator stop positions are set for another line. Thus in caseit is desirable to retain the tabulator stop positions, a function ofregistering such stop positions and recalling them later is quiteuseful. FIG. 33 shows the procedure of registering the tabulator stoppositions, in which the OP CONTROL key is actuated to light the STORElamp, then the FORMAT key is actuated to light the FORMAT lamp, and aparticular title name which should start with a numeral is entered. Ifthe same title name already exists, an alarm is given in the same manneras explained in the foregoing and the entered title name is notaccepted. Upon actuation of the RETURN key after the entry of the titlename, the data for tabulator stop positions already stored in theregisters TAB1-TABn by the SPACE or SET key are registered in thesentence memory 54. FIG. 34 shows the procedure of recalling such stoppositions, in which executed in succession are the actuation of the OPCONTROL key to turn off the STORE lamp, actuation of the FORMAT key toturn on the FORMAT lamp, entry of the title name for the registeredtabulator stop positions, actuation of the RETURN key and the key,whereupon the carriage 26 is automatically shifted to the first of theregistered tabulator stop positions.

The functions of the above key operations are explained in thefollowing. FIG. 35 shows how FIGS. 35-1 and 35-2 should be arranged.

Upon detection of the actuation of the FORMAT key by the MPU 44, theprogram proceeds to the sequence FORMAT shown in FIGS. 35-1 and 35-2.The program first clears a line counter LC for counting the number oflines on the printing sheet P, then checks the flag STR, and, if saidflag is set by the STORE mode of the OP CONTROL key, executes theregistration of the page format or the tabulator stop positions. In casesaid flag STR is not set, there is conducted the readout of the pageformat or the tabulator stop positions according to the format readoutsequence FMRD shown in FIG. 36. In the sequence FORMAT shown in FIGS.35-1 and 35-2, if the flag STR is set, the program enters a key entrywaiting step KEY INT.

In response to the entry of the title name, the line buffer storageroutine LBFSTR is initiated to store the title name in the line buffer52 and display the same on the display unit 9. Then actuated is theRETURN key in order to indicate the completion of the title name entry.Since the flag TR is not set in this state, the buffer printing sequenceBFPRT is executed to print the title name, to return the carriage 26 tothe left margin stop position, to advance the printing sheet P by aline, and to set the flag TR. Then the program checks the content of thefirst digit of the line buffer (LB) 52, and, if it is a numeral,proceeds to the YES branch to store the title name of the line buffer(LB) 52 starting with a numeral and the data of tabulator stop positionsstored in the registers TAB1-TABn into the sentence memory 54.

In case said title name starts with a character indicating theregistration of a page format, the title name in the line buffer (LB) 52is diverted into the WORK register for continuing the display. Then thecarriage 26 is displaced to an entry point EP1, EP2, etc. by means ofthe SPACE key, etc. and the key is actuated to divert the content of theregister CRGPT, indicating the carriage distance from the left-endreference point, into the WORK register. In case there are plural entrypoints EP1-EP11 as shown in FIG. 30, the content of the register CRGPTis stored in the WORK register in succession by repeating the actuationsof the SPACE key and the key. Upon completion of the registration ofentry points EP1, etc. in a line, the RETURN key is actuated. Since theflag TR is set in this state, the program proceeds to the YES branch toset the line counter LC from 0 to 1, and stores the content thereof inthe WORK register corresponding to the storage of the entry point EP1,etc.

The above-mentioned procedure is repeated for the number of lines in thepage format, thereby storing the entry point data of every line in theWORK register. Upon actuation of the FORMAT key, the content of saidWORK register, including the title name, line number, and entry pointsEP1, etc. in each line, is registered in the sentence memory 54, and theFORMAT lamp is turned off to complete the registration of the pageformat.

In the readout of the thus registered page format, the OP CONTROL key isset to a mode other than the STORE mode to reset the flag STR. Thus inresponse to the actuation of the FORMAT key, the program proceeds, inthe step STR=1?, to the NO branch to execute the format readout sequenceFMRD shown in FIG. 36. In response to the entry of the title name of thepage format or tabulator stop positions the line buffer storage sequenceLBFSTR is executed to display the title name, and in response to theactuation of the RETURN key the program proceeds, in the step TR=1?, tothe NO branch in the aforementioned manner. Then the first digit of theline buffer (LB) 52 is checked, and, if it is a numeral indicating atitle name for the tabulator stop position, the data of the tabulatorstop positions in the sentence memory 54 corresponding to said titlename are transferred to the registers TAB1-TABn for again setting thetabulator stop positions. The contents of said registers TAB1-TABn aresensed by the MPU 44 to restore the data of the previous tabulator stoppositions, thus enabling automatic tabulator setting of the carriage 26.

Also in case of a title name starting with a character indicating a pageformat, the page format corresponding to said title name in the sentencememory 54 is transferred to the WORK register and the flag TR is set.Thereafter in response to the actuation of the key, the data for theentry points EP1-EP11 in the WORK register are supplied to the MPU 44 toautomatically displace the carriage 26 to the entry point EP1 forexample. Thus, in the example shown in FIG. 30, automatic carriagedisplacement and sheet feeding for the entry points EP1-EP11 is effectedby actuating the key eleven times without touching the RETURN key. Thisis due to the fact that the sentence memory 54 remembers the carriagereturn commands and the amount of sheet feeding instructed by the RETURNkey at the registration of the page format.

Also at the readout from the sentence memory 54, the data stored thereinoverride the state of the PITCH, LINE SPACE, and OP CONTROL keysselected at the keyboard 10. For example, when the page format isrecalled and the carriage 26 is displaced to an entry point EP1 forexample by the key, the actuation of a character key 10a provides thecharacter-unit printing mode (C-mode) even if the OP CONTROL key is setat the W-mode for the word-unit printing, since the sequence BFPRT inLBFSTR in FIG. 36 is not executed as shown in FIG. 24 but is executedthe next time because of the state TR=1.

In this manner the printing from the entry point EP1 for example can beconveniently conducted in response to each entry of the character. Alsoduring the readout function of the page format the title name of saidpage format is continuously displayed by the sequence LBFSTR so that itis possible to locate a mistake in the selection of the registered pageformat.

Now reference is made to FIGS. 37 to 39-2 showing an embodiment allowingeasy correction or insertion of printed characters.

In the print unit equipped in the conventional office computer orcalculator or in the key-controlled printer such as an electronictypewriter, the correction or insertion of printed characters can onlybe made by the displacement of the carriage or printing sheet throughvisual observation or by manual operation with special correctingutensils on the printing sheet removed from the printer and hastherefore been an extremely cumbersome operation even for an experiencedoperator.

The present embodiment explained in the following is capable of avoidingsuch difficulties.

FIG. 37 shows an example of printing on a printing sheet P, in which thecharacters, A, B, a, b, etc. are printed at arbitrary positions underthe key instructions, by means of the displacement from left to right ofa carriage 26 supporting for example a daisy typefont wheel 30.

For the lower case characters a, b, etc. the line spacing can be reducedfor example to 3/4.

FIG. 38 shows an embodiment of the printer in a block diagram, whereinletters are used to designate block representations of units which weredesignated by numerals in the more detailed Figures. The block diagramshows a keyboard KBD comprising alphabet keys KAa-KZz, numeral keysKN0-KN9 shown in FIG. 44, and control keys K1-K6 for giving variouscommands to the carriage CA; a central processing unit CPU; a paper feedcontrol PF which controls a roller RO for the feeding of the printingsheet P; a drive control unit HD for a typefont wheel WH; a carriage CAsupporting said typefont wheel WH and performing displacement in thelateral direction; and a drive control unit CD for the carriage CA. Acarriage position counter CC for detecting the carriage position storesthe displacing distance of the carriage CA by counting the drive pulsesfor a stepping motor CM for said carriage CA. Also provided is a memoryor line buffer LB for the correction or insertion of the printedcharacters and provided with a capacity for 300 characters over 2 lines.Inside said memory LB each memory area for a character is divided intothree addresses I, II and III, wherein the address I stores the kind ofcharacter such as A, B, a, b, =, $, etc. in coded form, the address IIstores the printing pitch or the amount of carriage displacementcorresponding to the size of each printed character, even when saidprinting pitch is the same as that for the neighboring characters, andthe address III stores the kind of type such as printing with anunderline.

It is now assumed that the printing pitch is equal to a constant unitpitch 1PT regardless of the size of the printed character, that the kindof type does not include special printing type such as underlinedprinting but is limited to an ordinary printing of characters NMP, andthat the feed pitch of the printing sheet P is limited to an ordinaryunit pitch 1PF. By the actuation of a carriage return (CR) key K1 thecarriage CA is displaced to the left-hand end of the sheet P, which issimultaneously advanced by a line. Now, upon entry of a character A fromthe keyboard KBD, an address circuit AD instructs the storage of a coderepresenting the character A in the address I of the first memory area 1in the line buffer LB, a code 1PT representing said constant printingpitch in the address II, and a code NMP representing a simple printingin the address III.

When the type A is brought to the printing position by the rotation ofthe typefont wheel WH, the CPU reads the content of the address I of thefirst memory area 1 of said line buffer LB to print the character A inthe 1st line and in the 1st column as shown in FIG. 37, and the carriageCA is displaced to the right by one digit amount under the control ofthe carriage drive control unit CD. Then, upon entry of the nextcharacter B from the keyboard KBD the address circuit AD is stepadvanced to store a code for the character B in the address I of thesecond memory area 2 in the line buffer LB and to store the data 1PT andNMP in the addresses II and III in the same manner as for the precedingcharacter A.

The CPU receives the data from the address I of the second memory area 2indicated by the address circuit AD, and prints the character B in the1st line and 2nd column as shown in FIG. 37 through a known coincidenceprocedure.

In this state the content of the carriage position counter CC is stepadvanced to "2" indicating the distance of the carriage CA from theleft-end position.

Similarly in response to the entries of characters C and D from thekeyboard KBD the address circuit AD stores the codes for C and D in theaddresses I of the 3rd and 4th memory areas 3, 4 and the codes 1PT andNMP in the addresses II and III. The CPU prints said characters C and Din the 3rd and 4th columns of the 1st line as shown in FIG. 37, and thecarriage position counter CC stores "4" indicating the distance of thecarriage CA from the left-end position. Then in response to theactuation of the carriage return (CR) key K1 in the keyboard KBD, theaddress circuit AD stores a code RET representing the returning orreverse displacement of the carriage CA in the address I of the 5thmemory area 5 in the line buffer LB. It also stores, in the address II,a code 4ST representing the carriage displacement "4" from the left-endposition obtained from the carriage position counter CC, and, in theaddress III, a code 1PF representing the ordinary sheet feeding pitch.

FIG. 39 shows how FIGS. 39-1 and 39-2 should be arranged. FIGS. 39-1 and39-2 show the state of data storage in the line buffer LB. At this pointthe carriage CA is returned to the left-end position, and the printingsheet P is advanced upwards in the known manner by the rotation of arubber roller RO by an ordinary line pitch 1PF. Also the carriageposition counter CC in the carriage drive control unit CD is reset. Thena space (SP) key K3 in the keyboard KBD is actuated to displace thecarriage CA to the right by one character in order to form a space inthe 2nd line as shown in FIG. 37. Simultaneously the address circuit ADstores a code SPA representing a blank space in the address I of the 6thmemory area 6 in the line buffer LB, a code 1PT indicating the printingpitch in the address II, and a code NOP indicating absence of printingin the address III. Also the carriage position counter CC has a count"2" in the same manner as explained in the foregoing. Then in responseto the entries of the characters E and F, the corresponding charactercodes, printing pitches, and kinds of type are stored in the addressesI, II, and III in the 7th and 8th memory areas 7, 8 of the line bufferLB. The characters E and F are printed as shown in FIG. 37, and thecarriage position counter CC stores "3". Let us assume that it is foundat this point that the character C in the 3rd column of the 1st lineneeds to be corrected for example to a character Y. Upon actuation of aback trace (BT) key K2 provided exclusively for correction or insertion,the CPU reads, by stepwise reversing the address circuit AD, the contentof the 7th memory area 7 of the line buffer LB to obtain the codes NMPand 1PT as shown in FIGS. 39-1 and 39-2, whereby the CPU shifts thecarriage CA to the left by one character pitch 1PT. Upon anotheractuation of the back trace (BT) key K2, the address circuit AD ischanged from "7" to "6" to indicate the sixth memory area 6 in the linebuffer LB, in response to which CPU shifts the carriage CA by one pitch1PT toward the left-end position. Upon one more actuation of the backtrace (BT) key K2, the CPU decodes the 5th memory area 5 to find thedata for line feed for one pitch 1PF, carriage displacement for 4 steps,and carriage return command, whereby the carriage CA is displaced 4steps, to the right and is stopped automatically at the character D inthe 4th column of the 1st line shown in FIG. 37. At the same time theprinting sheet P is inversely fed downwards by the inverse rotation ofthe rubber roller RO.

In this manner the carriage CA can be automatically brought to theposition of the last character in the preceding line. Thus, upon afurther actuation of the back trace (BT) key K2, the carriage CA isdisplaced leftwards by one pitch 1PT to the position of the character Cat the 3rd column in the 1st line, whereupon it is rendered possible toerase the character C with the correcting ribbon 33 by actuating thecorrection (CO) key K6 and to print the character Y anew by enteringsaid character, and the data in the line buffer LB is changed from C toY by the function of the address circuit AD. After the correction iscompleted by repetitive actuations of the back trace (BT) key K2 and thecorrection (CO) key K6, a relocate (RL) key K5 is actuated whereby theCPU reads the address "8" immediately before the actuation of the backtrace (BT) key K2, calculates the distance in the lateral direction andthat in the sheet feed direction from the present address to theoriginal address "8", and returns the carriage CA to a positionimmediately before the actuation of the key K2. Thereafter thecharacters G, H, and I are similarly entered and stored in succession inthe line buffer LB through the address circuit AD, and the carriageposition counter CC is advanced to "6". Upon completion of the printingof characters G, H, and I, the carriage return (CR) key K1 is actuatedto return the carriage CA to the left-end position and to advance theprinting sheet P by one line 1PF. In case the lower-case characters areto be printed in the 3rd line, the line spacing for sheet advancement bythe key K1 is changed from 1 line for example to 3/4 line by giving acorresponding instruction from the keyboard KBD prior to the actuationof the key K1. Thereafter the lower-case characters a, b, c, . . . areprinted in the similar manner, and the lower-case characters h, i, . . .are printed in the 4th line after the sheet advancement of 3/4 line toobtain the print as shown in FIG. 37. As explained in the foregoing, theline buffer LB in succession stores the character information, carriagereturn command, carriage displacing distance, and sheet feed amount asshown in FIGS. 39-1 and 39-2. Also the backward displacement of thecarriage CA in the correcting operation can be achieved by actuating theback trace (BT) key K1 once and steadily pressing the repeat (RP) keyK4, whereby the address circuit AD repeats the subtraction to supply thecontents of the line buffer LB in succession to the CPU and to repeatthe reversing motion of the carriage CA. In this manner it is possibleto reach the position of correction at a high speed. Furthermore it ispossible to return the carriage CA to the previously printed lines byinstructing the number of lines of reversing motion with numeral keys KNin the keyboard KBD and by using the back trace (BT) key K2 and therepeat (RP) key K4.

More specifically it is possible, regardless of the number of lines, toreturn the carriage CA within a range of 300 characters.

As an example, when the carriage CA is at the 5th line in FIG. 37, it ispossible to return the carriage CA to the position of the character A atthe 1st column in the 1st line, by pressing the numeral key KN4 and byactuating the keys K2 and K4. For this purpose there can be provided aregister CS for storing said number "4", and the carriage CA is notstopped at each carriage return command but only at such carriage returncommand when the number of said commands coincides with the numberstored in said register CS.

The control method with a line buffer LB as employed in the presentembodiment is practically useful, since the case of printing a maximumof 150 characters on a sheet is rather seldom.

Furthermore it is in fact not necessary to store every carriage returncommand, displacing distance, and amount of sheet feeding as shown inthe 34th and 35th memory areas in FIGS. 39-1 and 39-2, since the sheetfeeding may be conducted manually and the carriage return command itselfcan be included in the data of distance of carriage displacement.

Also the line buffer LB is preferably backed upon with a battery BAT asshown in FIG. 38, in order to retain the content even when the powersupply is interrupted for some reason and thus to facilitate thecorrection, after the re-start of the function, on the work done beforethe interruption of the power supply.

Now reference is made to FIGS. 40, 41, and 42 showing a printer capableof printing form lines by the key operations. FIG. 40 shows anembodiment WH of part of a typefront wheel 30. FIGS. 41 and 42 showsamples of printing on a printing sheet P.

Conventionally patterns other than characters and numerals, such as formlines, must be inscribed with a scale and a ball-point pen, etc. andtherefore cannot be made neatly.

In consideration of the foregoing difficulty, the present embodimentenables the printing of form lines with neatly formed corners byselective use of vertical-line and horizontal-line types with keyoperations.

FIG. 40 shows a part of an example of a daisy typefront wheel WH adaptedfor use in the present embodiment. Said typefront wheel WH is provided,in addition to the ordinary types CT, with a vertical-line type CV andhorizontal-line types CH1, CH2 for forming the vertical and horizontalform lines as shown in FIGS. 41 and 42. The type CH1 is providedapproximately in the center of a type area and is utilized for printinga minus symbol "-" as shown in the 2nd column in the 1st line in FIG.41, whereas the type CH2 is provided at the lower part of a type areaand is utilized for printing an underline as shown in the 2nd, 3rd, 4th,and 5th columns in the 3rd line in FIG. 41. Also the type CV is utilizedfor printing various vertical lines as shown at the 1st column in the1st to 3rd lines and 6th to 11th lines in FIG. 41, and at the 1st columnin the 7th to 11th lines, at the 7th and 9th columns in the 8th to 10thlines, and at the 3rd and 6th columns in the 12th line in FIG. 42. Asshown in FIGS. 41 and 42, the printer of the present embodiments iscapable of forming vertical and horizontal lines with types controlledby key operations and without particular scale or other writingutensils.

However, in the form line printing shown in FIG. 41, the obtained formis not aesthetic in that the horizontal line at the 1st column in the3rd line is broken by a half pitch, that the horizontal line at the 1stcolumn in the 5th line is excessively long, and that the horizontal lineconstituting the underline for the characters E, F, G, and H in the 3rdline is too close to said characters.

These drawbacks can also be prevented by the present embodiment shown inFIG. 43 in a block diagram, wherein letters are used to designate blockrepresentative of units which were designated by numerals in the moredetailed Figures. In said block diagram, a keyboard KBD is provided witha vertical-line print key KV, a horizontal-line print key KH, a repeatprint key KR, a line spacing key KP for changing the type spacing orline feeding to a half, a backspace key KA, a shift key KS for usingsaid keys KP, KH, etc. for two purposes, in addition to other knowncharacter keys, numeral keys, control keys, etc. (not shown).

Also there are provided a central processing unit CPU, a control circuitCD for a carriage drive motor CM, a control circuit PD for a sheet feedmotor PM, a carriage CA supporting the typefront wheel WH shown in FIG.40, and a printing sheet P. In case of printing the vertical line asshown in FIGS. 41 and 42, the known control keys are actuated fordisplacing the carriage CA to the right or to the left. In response toCPU activates the drive circuit CD and releases a right-shift (forward)signal 1FC or a left-shift (backward) signal 1BC through a signal linel1 or l2 respectively to rotate the carriage drive motor CM in theforward or backward directon respectively through an OR gate OR1 therebystepwise displacing the carriage CA to a desired position for example inthe 1st column. Then in response to the actuation of the key KV, aflip-flop FV in the CPU is set and a vertical line "|" is printed forexample at the 1st column in the 7th line on the printing sheet P.

Then in response to the actuation of the repeat key KR, the CPU releasesa forward sheet feed signal 1FP through a line l5 of the control circuitPD to drive the sheet feeding motor PM through an OR gate OR2, therebyadvancing the printing sheet P by one line through the rotation of theroller RO.

Then upon actuation of the repeat key KR the vertical line "|" isprinted in the same column of the next line since the flip-flop FV ismaintained in the set state. In this manner said vertical line isprinted at the same column position in response to each actuation of thekey KR. Also an excessive printing eventually made can be erased in theknown manner with the correcting ribbon 33 through corresponding keyoperation.

In case of printing the horizontal line "-", in response to theactuations of the shift key KS and the key KH in this order, the CPUresets the flip-flop FV. However, the printing of a horizontal line withthe carriage CA positioned at the 1st column as shown before will resultin a form line as shown in the 1st column, 5th line in FIG. 41. In orderto avoid such defective line printing, the key KP is actuated after theshift key KS is actuated. In response the CPU releases a half-spaceright-shift (forward) signal 1/2FC to the line l3 of the control circuitCD to displace the carriage CA to the right by 1/2 space. In this mannerthe carriage CA becomes positioned between the 1st and 2nd column, sothat the horizontal line "-" obtained by the actuation of the key KH ispositioned between the 1st and 2nd columns as shown in the 5th and 11thlines in FIG. 42. Also in case the carriage CA is originally positionedin another place, it can be brought to a position between the 1st and2nd columns by actuating the known back space key KA for a desirednumber of times followed by the actuation of the key KP, whereby theleft-shift (backward) signal 1BC and the half-space left-shift(backward) signal 1/2BC are supplied to the lines l2 and l4 respectivelyof the control circuit CD. Also as shown in the 7th and 9th columns inthe 8th to 10th lines in FIG. 42, the vertical line "|" can be suitablyshifted by a half space to the left or to the right by the keys KV, KP,and eventually KA to provide vertical lines for a matrix well balancedwith the positions of the printing d1-d3, c1-c3, etc. Theabove-mentioned half-space process can further be applied to the sheetadvancement to provide an easily legible printed form. For this purposethe control circuit PD for the sheet advancement is provided with signallines l5 to l8 for selectively providing the one-line forward orbackward advance signals 1FP and 1BP respectively and half-line forwardor backward advance signals 1/2FP and 1/2BP respectively.

For example in response to the actuation of the key KP, the CPU providesthe signal 1/2FP through the output line l7 of the control circuit PD toadvance the printing sheet P by a half line. Also in response to theactuations of the shift keys KS and key KP, the carriage CA is moved tothe right by a half space through the output line l3 of the controlcircuit CD. By actuating character keys E, F, G, and H, these charactersare printed in the middle positions of the columns and lines as shown inFIG. 42, maintaining suitable spaces from the form lines above and atleft. Also by said half-line sheet feeding the horizontal line at the9th column in the 9th line becomes suitably positioned with respect tothe characters "D" and "1" in spite of the fact that the type for saidhorizontal line is positioned at the lower end of the type area as shownin FIG. 42.

Also the vertical line "|" can additionally be used for various purposessuch as in indicating the date as shown at the 3rd and 6th columns inthe 12th line in FIG. 42.

As explained in the foregoing, the present embodiment allows obtainingeasily legible print formats by the use of vertical-line andhorizontal-line type in combination with a half-space displacement ofthe carriage CA and a half-line displacement of the printing sheet Punder suitable key control, and such print formats are more legible thanthose obtained by dot matrix printing.

FIGS. 44, 45, 46A, and 46B show an embodiment of the electronic devicecapable of increasing the print processing speed and providing morelegible print forms.

For example in the conventional desk-top electronic calculator with aprinter, an entered number is printed only when an operand key, such as"+", is actuated following the entry of numerals, and for this reasonthe printing of the entire number requires a certain time.

This drawback is prevented by the present embodiment in which theprinting of the integer part of a number is initiated at the entry ofthe decimal point, with appropriate punctuation in said integer part. Inthis manner it is rendered possible to shorten the processing time asthe integer part can be printed while the decimal fraction part of thenumber is entered by the numeral keys KN, to reduce errors in key entryas the numerals are printed with appropriate punctuation, and to avoiduseless entries of the decimal fraction part in case an error is foundin the entry of the integer part.

FIG. 44 shows the present embodiment in a block diagram, in whichletters are used to designate block representations of units which weredesignated by numerals in the more detailed Figures. The block diagramshows a keyboard KBD which is provided with numeral keys KN0-KN9, adecimal point key KP, a slide switch SS for selecting punctuation byblank or by a particular symbol (,), a control key KD for numeralprinting with a fixed decimal point position, and control keys KC (K+,K-, KX, K, K%, K=). Also there are shown a register KR for storing thekey signals from the keyboard KBD, a number display unit DSP, a centralprocessing unit CPU, and a printer PRT having a serial printing head Hfor printing from left to right on a printing sheet P. FIG. 45 shows anexample of the printing, and FIGS. 46A and 46B illustrate the order ofthe display and printing.

By first manipulating for example a numeral key KN8 followed by thecontrol key KD, the datum "8" is stored in a latch L in the CPU to fixthe position of the decimal point at the 8th column from the left-handend of the printing sheet P.

Now, upon actuation of the numeral key KN1, the numeral "1" is stored inthe register KR and displayed on the display unit DSP, and then uponactuation of the numeral key KN2, the numeral "2" is also stored in theregister KR and a number "12" is displayed on the display unit DSP asshown in FIG. 46A, part I. No printing is made at this stage.

Also a counter C in the CPU stores a number "2" indicating the number ofnumeral key actuations. Then, in response to the actuation of thedecimal point key KP, the CPU substracts "2" stored in the counter Cfrom "8" stored in the latch L to obtain the difference "6", anddisplaces the printing head H to the 6th column from the left-hand endof the printing sheet P to print a numeral "1" at this position, then toprint a numeral "2" to the right, and then to print the decimal point"." further to the right as shown in FIG. 46B, part I. During saidprinting the fraction part "34" can be entered by the numeral keys KNand is displayed on the display unit DSP as shown in FIG. 46A, part II.Upon subsequent actuation of a control key KC the printing head H isdisplaced in succession to the right to print the numerals "3" and " 4"as shown in FIGS. 45 and 46B, part II. During said printing it ispossible to enter the numerals for the printing in the next line. Atthis point the counter C is cleared but the content "8" of the latch Lis retained. Upon completion of the printing "34" the printing sheet Pis advanced by a line, and the printing head H is in a stand-by statefor the printing of the next line. Then the numerals in "123456" areentered by the numeral keys KN1-KN6 and are displayed on the displayunit DSP (FIG. 46A, part III) through the register KR as explained inthe foregoing, and the counter C stores a number "6". Upon actuation ofthe decimal point key KP, the CPU senses the possibility of punctuationfrom the number "6" in the counter C, adds "1" to the counter C toobtain "7", and subtracts said number "7" from "8" stored in the latch Lto obtain "1" in the foregoing manner, whereby the printing head Hinitiates the printing from the left-hand end of the printing sheet P.At the same time the CPU senses the state of the slide switch SS, whichis set at the blank punctuation state in FIG. 44, to execute theprinting with blank punctuations (FIG. 46B, part III). The entry andprinting of the fraction part and the line feed operation are conductedas explained in the foregoing.

In case the slide switch SS is set at ",", the print is punctuated withthe symbol "," as exemplified by "7,654.321" in FIGS. 45 and 46B, partVI.

As explained in the foregoing the present embodiment is advantageous inreducing the errors in operation as the integer part is immediatelyprinted with appropriate punctuation in response to the actuation of thedecimal point key KD1, thus providing an easily legible print with afixed decimal point position and increasing the processing speed. Thusthe present embodiment has a wide range of applications, particularlyincluding electronic typewriters.

FIG. 47 shows the manner in which FIGS. 47-1 and 47-2 should bearranged. FIGS. 47-1 and 47-2 show an embodiment of the electronictypewriter, particularly the electronic typewriter provided with adisplay unit 9 for displaying the characters to be printed and acharacter generator 100 for generating character information fordisplay.

The use of character generators in the electronic typewriter is alreadyknown, but for displaying the characters used in various countries therehave been required a character generator and a control circuit of a verylarge capacity. For this reason it has been a common practice to mount acharacter generator suitable for the country of destination, althoughthis complicates the specifications of the typewriter and necessitatesthe operation of replacement work.

Thus, the present embodiment provides an electronic typewriter capableof displaying the characters of various countries without increasing thecapacity of the memory.

Now reference is made to FIGS. 47-1 and 47-2 showing the basic structureof such an electronic typewriter, in which a keyboard 10 is providedwith character keys 10a common to various countries and with characterkeys 10h exclusive to the country of destination. The entered keysignals for printing are first displayed on a display unit 9.

There are provided an oscillator 90 for generating a basic frequency fordynamic drive of the display unit 9; a counter 91 of a capacity of thenumber of digits of the display unit 9; a decoder 92 for generating adigit signal corresponding to the count of said counter 91; a digitdriver 93; and a multiplexer 102 for supplying the count of the counter91 or a signal supplied from the MPU 44 through an address bus AB to adisplay buffer 101 as an address signal thereto. Said display buffer 101is capable of storing the character signals entered from the keyboard 10at least for the capacity of the display unit 9, for example 20characters. By designating the display buffer 101 from the addressdecoder 105, the multiplexer 102 provides the signal of the address busAB to the display buffer 101 as the address signal therefor, and thecharacter signal in the display buffer 101 is made changeable by thesignal from the data bus DB. A main character generator (CG) 100 forcommon characters converts the character signals from the display buffer101 into character font represented in dot matrix form. A secondarycharacter generator 106 stores the typefronts for particular countriesand has a capacity corresponding to the countries of destination. Amultiplexer 97 provides the character font from the main charactergenerator 100 or from the data bus DB to the latch 96. A driver 95drives the display unit 9 in response to the signal from said latch 96.A manual switch 98 composed for example of selectable diodes in a matrixarray is utilized for selecting a country in the secondary charactergenerator 106. A bus driver 99 transmits the information of the switch98 to the MPU 44. In case of displaying the common characters 10a, thedigit signal indicated by the count of the counter 91 is supplied to thedisplay unit 9 through the decoder 92 and the digit driver 93, and thecorresponding character signal is read from the display buffer 101addressed by the count of said counter 91 through the multiplexer 102.Said character signal is converted into a character pattern by the maincharacter generator (CG) 100, then latched in the latch 96 through themultiplexer 97 and supplied to the display unit 9 through the driver 95for display in cooperation with the digit signal corresponding to thecontent of the counter 91. A dynamic display is achieved by repeatingthe above-mentioned procedure with the frequency of the oscillator 90.There are also provided a memory 103 for storing the reference charactersignal and a comparator 104.

Since certain vowels, currency marks, etc. are different from country tocountry, the character generator 100 needs to have an enormous capacityif all these characters are to be incorporated therein, and thecharacter generator 100 itself needs to be remade if a country ofdestination is added. However, in the present embodiment the charactergenerator 100 only contains the characters, numerals, and symbols commonto all the countries, and the memory 103 and comparator 104 inspect forcharacters not contained in the character generator 100, and, upondetection of such a character, set a flip-flop 107 to supply aninterruption signal INT to the MPU 44. The MPU 44, already identifyingthe country of designation by the state of the switch 98 through the busdriver 99, discriminates the character signal for which the interruptionsignal INT is given. Based on said character signal the MPU 44 generatesthe address signal for the secondary character generator 106 andsupplies the character signal therefrom through the data bus DB andmultiplexer 97 to the latch 96. In this manner the adjustment for thechange of country of destination can be simply accomplished byappropriately positioning the switch 98 in the secondary charactergenerator 106.

Let us assume now that the main character generator 100 stores a commoncharacter font composed of A, B, C, D, E, and F each composed of 5×12dots, and that the following codes are allotted for the characters inthe display buffer 101:

A: 000

B: 001

C: 010

D: 011

E: 100

F: 101

Also it is assumed that the following codes are allotted for thecurrency marks of specified countries:

: 110

$: 111

In this case a reference signal "101" is stored in the memory 103, andthe comparator 104 is so structed as to set the flip-flop 107 forinitiating the interruption procedure upon receipt of a signal largerthan said signal "101".

The secondary character generator 106 stores the character fontcorresponding to the currency marks and $.

The keyboard 10 shown in FIG. 47-2 is designed for Japan and is providedwith common keys 10a and exclusive key 10h, a Yen currency key " ", andthe switch 98 is set for Japan.

In response to the actuation of the " " key 10h, the MPU 44, beingalready aware that the switch 98 is set for Japan, stores a code "110"in the display buffer 101, and the comparator 104 compares said codewith the reference signal "101" stored in the memory 103 and, the latterbeing smaller, sets the flip-flop 107 thereby sending an interruptionsignal INT to the MPU 44 indicating a character other than those storedin the main character generator 100. Simultaneously receiving the code=110 through the data bus DB, the MPU 44 generates an address signal forcalling the character in the secondary character generator 106 throughthe address bus AB and supplies said character into the multiplexer 97through the bus driver 99 to display the character on the display unit9.

On the other hand the switch 98 is set to the United States when thekeyboard 10 for the United States shown in FIG. 48 is mounted. In thismanner the MPU 44 knows that the apparatus is adjusted for the UnitedStates and, in response to the actuation of the exclusive "$" key 10h,generates a code "111" for storage in the display buffer 101. Thecomparator 104, similarly identifying that the reference code "101" issmaller, releases the interruption signal INT in the same manner asexplained in the foregoing. In this case the MPU 44 receives the code"111" through the data bus DB and thus addresses the character $ in thesecondary character 106.

As explained in the foregoing the present embodiment employs a maincharacter generator storing common characters and symbols and asecondary character generator storing characters and symbols changingfrom country to country, and performs the display usually with the maincharacter generator but with the secondary character generator only whenthe desired character is not present in the main character generator.Consequently the adjustment for each country can simply be achieved byappropriate positioning of the switch.

We claim is:
 1. A printing apparatus for printing on printing paper,comprising:carriage means movable relative to a printing paper; an inkribbon mounted on said carriage means for advancement; type meansmounted on said carriage means for carrying a plurality of typeelements; a hammer mounted on said carriage means for striking any ofsaid type elements carried on said type means against the printingpaper; a first pulse motor for advancing the printing paper; a secondpulse motor for advancing said ink ribbon; means for actuating saidhammer; first pulse generating means for generating a first pulsesequence; second pulse generating means for generating a second pulsesequence; third pulse generating means for generating a third pulsesequence; first selecting means for selecting one of a plurality ofamounts of advancement of said printing paper; second selecting meansfor selecting one of a plurality of amounts of advancement of said inkribbon; third selecting means for selecting one of a plurality of timeintervals of actuation of said hammer; first counting means for countingpulses from said first pulse generating means up to a first set valuedetermined by the amount of paper advancement selected by said firstselecting means; second counting means for counting pulses from saidsecond pulse generating means up to a second set value determined by theamount of ribbon advancement selected by said second selecting means;third counting means for counting pulses from said third pulsegenerating means up to a third set value determined by the time intervalof hammer actuation selected by said third selecting means; firstcontrol means for starting advancement of said printing paper by saidfirst pulse motor upon selection of one of the amounts of advancement ofsaid printing paper by said first selecting means and for controllingsaid first pulse motor to advance said printing paper until the count bysaid first counting means reaches said first set value; second controlmeans for starting advancement of said ink ribbon by said ribbonadvancing means upon selection of one of the amounts of advancement ofsaid ink ribbon by said second selecting means and for controlling saidsecond pulse motor to advance said ink ribbon unti the count by saidsecond counting means reaches said second set value; third control meansfor starting actuation of said hammer by said hammer actuating meansupon selection of one of the time intervals of actuation of said hammerby said third selecting means and for controlling actuation of saidhammer by said hammer actuating means until the count by said thirdcounting means reaches said third set value; and processing means forcontrolling operation of each of said first, second and third countingmeans and each of said first, second and third control means.
 2. Aprinting apparatus according to claim 1 wherein each said counting meansincludes a subtracting counter and a zero detector for detecting whenthe count by said subtracting counter reaches zero.
 3. A printingapparatus according to claim 1, wherein said first and second pulsemotors are respectively driven by the outputs of said first and secondpulse generating means.